Mutex: remove Abseil static initializer.

The change adds conditional inclusion of mutex_abseil.h from mutex.h
and conditional referencing of
//third_party/abseil-cpp/absl/synchronization
which introduces a static initializer.

https://webrtc-review.googlesource.com/c/src/+/176230 introduced a
static initializer which broke the Chromium autoroll,
https://chromium-review.googlesource.com/c/chromium/src/+/2230887.
Example failure:
https://ci.chromium.org/p/chromium/builders/try/android-lollipop-arm-rel/34133

TBR=karl@webrtc.org

No-Try: True
Bug: webrtc:11567
Change-Id: Id78af798f34d5d6beaf9f6e0150e6b3ddd31ff4f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/176513
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Olga Sharonova <olka@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31451}

1 files changed, 4 insertions, 0 deletions

diff --git a/BUILD.gn b/BUILD.gn
index 698e4cff70..adb78df424 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -265,6 +265,10 @@ config("common_config") {
     defines += [ "WEBRTC_USE_H264" ]
   }
 
+  if (rtc_use_absl_mutex) {
+    defines += [ "WEBRTC_ABSL_MUTEX" ]
+  }
+
   if (rtc_disable_logging) {
     defines += [ "RTC_DISABLE_LOGGING" ]
   }