Remove extern from function declared in headers. (#13790)

By default functions are declared as extern in C/C++ headers. The goal
of this PR is to reduce the wall of text that many headers have and,
more importantly, to make the declaration of extern'd variables - of
which we have many dispersed in various places - easily and quickly
identifiable.

Automatically generated with:

    $ git grep -l '^extern.*(' '**.h' | \
            grep -v libjudy | \
            grep -v 'sqlite3.h' | \
            xargs sed -i -e 's/extern \(.*(.*$\)/\1/'

This is a NFC.

8 files changed, 50 insertions, 50 deletions

diff --git a/daemon/analytics.h b/daemon/analytics.h
index 76c1cbb7e0..d1ffcec187 100644
--- a/daemon/analytics.h
+++ b/daemon/analytics.h
@@ -69,18 +69,18 @@ struct analytics_data {
     uint8_t dashboard_hits;
 };
 
-extern void analytics_get_data(char *name, BUFFER *wb);
-extern void set_late_global_environment(void);
-extern void analytics_free_data(void);
-extern void set_global_environment(void);
-extern void send_statistics(const char *action, const char *action_result, const char *action_data);
-extern void analytics_log_shell(void);
-extern void analytics_log_json(void);
-extern void analytics_log_prometheus(void);
-extern void analytics_log_dashboard(void);
-extern void analytics_gather_mutable_meta_data(void);
-extern void analytics_report_oom_score(long long int score);
-extern void get_system_timezone(void);
+void analytics_get_data(char *name, BUFFER *wb);
+void set_late_global_environment(void);
+void analytics_free_data(void);
+void set_global_environment(void);
+void send_statistics(const char *action, const char *action_result, const char *action_data);
+void analytics_log_shell(void);
+void analytics_log_json(void);
+void analytics_log_prometheus(void);
+void analytics_log_dashboard(void);
+void analytics_gather_mutable_meta_data(void);
+void analytics_report_oom_score(long long int score);
+void get_system_timezone(void);
 
 extern struct analytics_data analytics_data;
 
diff --git a/daemon/buildinfo.h b/daemon/buildinfo.h
index 542a0e92e0..d3b439fc39 100644
--- a/daemon/buildinfo.h
+++ b/daemon/buildinfo.h
@@ -3,12 +3,12 @@
 #ifndef NETDATA_BUILDINFO_H
 #define NETDATA_BUILDINFO_H 1
 
-extern void print_build_info(void);
+void print_build_info(void);
 
-extern void print_build_info_json(void);
+void print_build_info_json(void);
 
-extern char *get_value_from_key(char *buffer, char *key);
+char *get_value_from_key(char *buffer, char *key);
 
-extern void get_install_type(char **install_type, char **prebuilt_arch, char **prebuilt_dist);
+void get_install_type(char **install_type, char **prebuilt_arch, char **prebuilt_dist);
 
 #endif // NETDATA_BUILDINFO_H
diff --git a/daemon/commands.h b/daemon/commands.h
index 1253e2dc1c..f0e38ce93f 100644
--- a/daemon/commands.h
+++ b/daemon/commands.h
@@ -76,7 +76,7 @@ typedef struct command_info {
 typedef void (command_lock_t) (unsigned index);
 
 cmd_status_t execute_command(cmd_t idx, char *args, char **message);
-extern void commands_init(void);
-extern void commands_exit(void);
+void commands_init(void);
+void commands_exit(void);
 
 #endif //NETDATA_COMMANDS_H
diff --git a/daemon/daemon.h b/daemon/daemon.h
index bec3df9fc5..2a8a58ec66 100644
--- a/daemon/daemon.h
+++ b/daemon/daemon.h
@@ -3,14 +3,14 @@
 #ifndef NETDATA_DAEMON_H
 #define NETDATA_DAEMON_H 1
 
-extern int become_user(const char *username, int pid_fd);
+int become_user(const char *username, int pid_fd);
 
-extern int become_daemon(int dont_fork, const char *user);
+int become_daemon(int dont_fork, const char *user);
 
-extern void netdata_cleanup_and_exit(int i);
-extern void send_statistics(const char *action, const char *action_result, const char *action_data);
+void netdata_cleanup_and_exit(int i);
+void send_statistics(const char *action, const char *action_result, const char *action_data);
 
-extern void get_netdata_execution_path(void);
+void get_netdata_execution_path(void);
 
 extern char pidfile[];
 extern char exepath[];
diff --git a/daemon/global_statistics.h b/daemon/global_statistics.h
index 8d4a63d085..a54610b0ed 100644
--- a/daemon/global_statistics.h
+++ b/daemon/global_statistics.h
@@ -8,17 +8,17 @@
 // ----------------------------------------------------------------------------
 // global statistics
 
-extern void rrdr_query_completed(uint64_t db_points_read, uint64_t result_points_generated);
-extern void sqlite3_query_completed(bool success, bool busy, bool locked);
-extern void sqlite3_row_completed(void);
+void rrdr_query_completed(uint64_t db_points_read, uint64_t result_points_generated);
+void sqlite3_query_completed(bool success, bool busy, bool locked);
+void sqlite3_row_completed(void);
 
-extern void finished_web_request_statistics(uint64_t dt,
+void finished_web_request_statistics(uint64_t dt,
                                      uint64_t bytes_received,
                                      uint64_t bytes_sent,
                                      uint64_t content_size,
                                      uint64_t compressed_content_size);
 
-extern uint64_t web_client_connected(void);
-extern void web_client_disconnected(void);
+uint64_t web_client_connected(void);
+void web_client_disconnected(void);
 
 #endif /* NETDATA_GLOBAL_STATISTICS_H */
diff --git a/daemon/main.h b/daemon/main.h
index 63d6c5a095..a4e2b3aa71 100644
--- a/daemon/main.h
+++ b/daemon/main.h
@@ -22,9 +22,9 @@ struct option_def {
     const char *default_value;
 };
 
-extern void cancel_main_threads(void);
-extern int killpid(pid_t pid);
-extern void netdata_cleanup_and_exit(int ret) NORETURN;
-extern void send_statistics(const char *action, const char *action_result, const char *action_data);
+void cancel_main_threads(void);
+int killpid(pid_t pid);
+void netdata_cleanup_and_exit(int ret) NORETURN;
+void send_statistics(const char *action, const char *action_result, const char *action_data);
 
 #endif /* NETDATA_MAIN_H */
diff --git a/daemon/signals.h b/daemon/signals.h
index 3fa2b0f43f..12b1ed198b 100644
--- a/daemon/signals.h
+++ b/daemon/signals.h
@@ -3,11 +3,11 @@
 #ifndef NETDATA_SIGNALS_H
 #define NETDATA_SIGNALS_H 1
 
-extern void signals_init(void);
-extern void signals_block(void);
-extern void signals_unblock(void);
-extern void signals_restore_SIGCHLD(void);
-extern void signals_reset(void);
-extern void signals_handle(void) NORETURN;
+void signals_init(void);
+void signals_block(void);
+void signals_unblock(void);
+void signals_restore_SIGCHLD(void);
+void signals_reset(void);
+void signals_handle(void) NORETURN;
 
 #endif //NETDATA_SIGNALS_H
diff --git a/daemon/unit_test.h b/daemon/unit_test.h
index 2d2533afed..dab1368b6c 100644
--- a/daemon/unit_test.h
+++ b/daemon/unit_test.h
@@ -3,18 +3,18 @@
 #ifndef NETDATA_UNIT_TEST_H
 #define NETDATA_UNIT_TEST_H 1
 
-extern int unit_test_storage(void);
-extern int unit_test(long delay, long shift);
-extern int run_all_mockup_tests(void);
-extern int unit_test_str2ld(void);
-extern int unit_test_buffer(void);
-extern int unit_test_static_threads(void);
-extern int test_sqlite(void);
-extern int unit_test_bitmap256(void);
+int unit_test_storage(void);
+int unit_test(long delay, long shift);
+int run_all_mockup_tests(void);
+int unit_test_str2ld(void);
+int unit_test_buffer(void);
+int unit_test_static_threads(void);
+int test_sqlite(void);
+int unit_test_bitmap256(void);
 #ifdef ENABLE_DBENGINE
-extern int test_dbengine(void);
-extern void generate_dbengine_dataset(unsigned history_seconds);
-extern void dbengine_stress_test(unsigned TEST_DURATION_SEC, unsigned DSET_CHARTS, unsigned QUERY_THREADS,
+int test_dbengine(void);
+void generate_dbengine_dataset(unsigned history_seconds);
+void dbengine_stress_test(unsigned TEST_DURATION_SEC, unsigned DSET_CHARTS, unsigned QUERY_THREADS,
                                  unsigned RAMP_UP_SECONDS, unsigned PAGE_CACHE_MB, unsigned DISK_SPACE_MB);
 
 #endif