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.

1 files changed, 20 insertions, 20 deletions

diff --git a/health/health.h b/health/health.h
index aa7a5c65ed..fc6a874e9f 100644
--- a/health/health.h
+++ b/health/health.h
@@ -32,23 +32,23 @@ extern unsigned int default_health_enabled;
 
 extern char *silencers_filename;
 
-extern void health_init(void);
+void health_init(void);
 
-extern void health_reload(void);
+void health_reload(void);
 
-extern void health_aggregate_alarms(RRDHOST *host, BUFFER *wb, BUFFER* context, RRDCALC_STATUS status);
-extern void health_alarms2json(RRDHOST *host, BUFFER *wb, int all);
-extern void health_alarms_values2json(RRDHOST *host, BUFFER *wb, int all);
-extern void health_alarm_log2json(RRDHOST *host, BUFFER *wb, uint32_t after, char *chart);
+void health_aggregate_alarms(RRDHOST *host, BUFFER *wb, BUFFER* context, RRDCALC_STATUS status);
+void health_alarms2json(RRDHOST *host, BUFFER *wb, int all);
+void health_alarms_values2json(RRDHOST *host, BUFFER *wb, int all);
+void health_alarm_log2json(RRDHOST *host, BUFFER *wb, uint32_t after, char *chart);
 
 void health_api_v1_chart_variables2json(RRDSET *st, BUFFER *buf);
 void health_api_v1_chart_custom_variables2json(RRDSET *st, BUFFER *buf);
 
-extern int health_alarm_log_open(RRDHOST *host);
-extern void health_alarm_log_save(RRDHOST *host, ALARM_ENTRY *ae);
-extern void health_alarm_log_load(RRDHOST *host);
+int health_alarm_log_open(RRDHOST *host);
+void health_alarm_log_save(RRDHOST *host, ALARM_ENTRY *ae);
+void health_alarm_log_load(RRDHOST *host);
 
-extern ALARM_ENTRY* health_create_alarm_entry(
+ALARM_ENTRY* health_create_alarm_entry(
     RRDHOST *host,
     uint32_t alarm_id,
     uint32_t alarm_event_id,
@@ -74,20 +74,20 @@ extern ALARM_ENTRY* health_create_alarm_entry(
     int delay,
     uint32_t flags);
 
-extern void health_alarm_log_add_entry(RRDHOST *host, ALARM_ENTRY *ae);
+void health_alarm_log_add_entry(RRDHOST *host, ALARM_ENTRY *ae);
 
-extern void health_readdir(RRDHOST *host, const char *user_path, const char *stock_path, const char *subpath);
-extern char *health_user_config_dir(void);
-extern char *health_stock_config_dir(void);
-extern void health_alarm_log_free(RRDHOST *host);
+void health_readdir(RRDHOST *host, const char *user_path, const char *stock_path, const char *subpath);
+char *health_user_config_dir(void);
+char *health_stock_config_dir(void);
+void health_alarm_log_free(RRDHOST *host);
 
-extern void health_alarm_log_free_one_nochecks_nounlink(ALARM_ENTRY *ae);
+void health_alarm_log_free_one_nochecks_nounlink(ALARM_ENTRY *ae);
 
-extern void *health_cmdapi_thread(void *ptr);
+void *health_cmdapi_thread(void *ptr);
 
-extern void health_label_log_save(RRDHOST *host);
+void health_label_log_save(RRDHOST *host);
 
-extern char *health_edit_command_from_source(const char *source);
-extern void sql_refresh_hashes(void);
+char *health_edit_command_from_source(const char *source);
+void sql_refresh_hashes(void);
 
 #endif //NETDATA_HEALTH_H