Fix/suppress all javac warnings.

This is done in preparation to make all javac warnings into errors for
WebRTC targets.

Bug: webrtc:6597
Change-Id: I402043157bd75943adf0de52111e5a1bb179c6d1
Reviewed-on: https://webrtc-review.googlesource.com/15104
Commit-Queue: Sami Kalliomäki <sakal@webrtc.org>
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20450}

rtc_base/java/src/org/webrtc/ThreadUtils.java

@@ -143,6 +143,8 @@ public class ThreadUtils {
     return result;
   }
 
+  // TODO(sakal): This method is broken. It should be removed: crbug.com/webrtc/8456
+  @SuppressWarnings("WaitNotInLoop")
   public static void waitUninterruptibly(final Object object) {
     executeUninterruptibly(new BlockingOperation() {
       @Override