chore: refine feature flags (#1785)

Removes dependencies between Tokio feature flags. For example, `process`
should not depend on `sync` simply because it uses the `mpsc` channel.
Instead, feature flags represent **public** APIs that become available
with the feature enabled. When the feature is not enabled, the
functionality is removed. If another Tokio component requires the
functionality, it is stays as `pub(crate)`.

The threaded scheduler is now exposed under `rt-threaded`. This feature
flag only enables the threaded scheduler and does not include I/O,
networking, or time. Those features must be explictly enabled.

A `full` feature flag is added that enables all features.

`stdin`, `stdout`, `stderr` are exposed under `io-std`.

Macros are used to scope code by feature flag.

1 files changed, 0 insertions, 4 deletions

diff --git a/tokio/src/sync/tests/loom_list.rs b/tokio/src/sync/tests/loom_list.rs
index 4f7746d5..4067f865 100644
--- a/tokio/src/sync/tests/loom_list.rs
+++ b/tokio/src/sync/tests/loom_list.rs
@@ -21,17 +21,14 @@ fn smoke() {
                 for i in 0..NUM_MSG {
                     tx.push((th, i));
                 }
-                debug!(" + tx thread done");
             });
         }
 
         let mut next = vec![0; NUM_TX];
 
         loop {
-            debug!(" + rx.pop()");
             match rx.pop(&tx) {
                 Some(Value((th, v))) => {
-                    debug!(" + pop() -> Some(Value({}))", v);
                     assert_eq!(v, next[th]);
                     next[th] += 1;
 
@@ -43,7 +40,6 @@ fn smoke() {
                     panic!();
                 }
                 None => {
-                    debug!(" + pop() -> None");
                     thread::yield_now();
                 }
             }