dontInitializeUninitializedLocals on Qualcomm only

SH_INITIALIZE_UNINITIALIZED_LOCALS triggers a very unpredictable crash
in the shader compiler on Qualcomm Adreno (at least 4xx) on Marshmallow.

Bug: angleproject:2046
Change-Id: I9a109f7ff442b4e9d3880d137f1a55a19105bcef
Reviewed-on: https://chromium-review.googlesource.com/705930
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>

CONTRIBUTORS

@@ -41,6 +41,7 @@ Google Inc.
  Justin Schuh
  Scott Graham
  Corentin Wallez
+ Kai Ninomiya
 
 Adobe Systems Inc.
  Alexandru Chiculita

src/libANGLE/renderer/gl/renderergl_utils.cpp

@@ -1067,7 +1067,9 @@ void GenerateWorkarounds(const FunctionsGL *functions, WorkaroundsGL *workaround
 #endif
 
 #if defined(ANGLE_PLATFORM_ANDROID)
-    workarounds->dontInitializeUninitializedLocals = true;
+    // Triggers a bug on Marshmallow Adreno (4xx?) driver.
+    // http://anglebug.com/2046
+    workarounds->dontInitializeUninitializedLocals = IsQualcomm(vendor);
 #endif
 
     workarounds->finishDoesNotCauseQueriesToBeAvailable =