Workaround a (Windows) linker bug when doing a PGO build.

It looks like having a function that ends with "FATAL()" but doesn't also have a return value (even if it's useless).

This is causing a hang in link.exe when doing a PGO build (this has been blocking us from doing PGO builds for more than a month now). See for more details.

Review URL:

Cr-Commit-Position: refs/heads/master@{#9469}
diff --git a/webrtc/modules/audio_coding/main/acm2/ b/webrtc/modules/audio_coding/main/acm2/
index 4e665ea..5536ea4 100644
--- a/webrtc/modules/audio_coding/main/acm2/
+++ b/webrtc/modules/audio_coding/main/acm2/
@@ -272,6 +272,11 @@
 // TODO(henrik.lundin): Remove; not used.
 int AudioCodingModuleImpl::SendBitrate() const {
   FATAL() << "Deprecated";
+  // This return statement is required to workaround a bug in VS2013 Update 4
+  // when turning on the whole program optimizations. Without hit the linker
+  // will hang because it doesn't seem to find an exit path for this function.
+  // This is likely a bug in link.exe and would probably be fixed in VS2015.
+  return -1;
   //  CriticalSectionScoped lock(acm_crit_sect_);
   //  if (!codec_manager_.current_encoder()) {