Suppress implicit-fallthrough warnings in audioflinger etc.

Add FALLTHROUGH_INTENDED for clang compiler.

Bug: 112564944
Test: build with global -Wimplicit-fallthrough.
Change-Id: I8875bc7ed073aae84d5df97eb39c8c745ca627ef
diff --git a/services/audioflinger/Tracks.cpp b/services/audioflinger/Tracks.cpp
index a7c4253..6d25fb9 100644
--- a/services/audioflinger/Tracks.cpp
+++ b/services/audioflinger/Tracks.cpp
@@ -842,7 +842,7 @@
 
             // Offloaded track was draining, we need to carry on draining when resumed
             mResumeToStopping = true;
-            // fall through...
+            FALLTHROUGH_INTENDED;
         case ACTIVE:
         case RESUMING:
             mState = PAUSING;