Add LTO support for Android Chromium.

This is to add support for a Link-Time Optimizations experiment in Android Chromium. As it is disabled by default, it won't change anything for most configurations.
BUG=chromium:407544
R=andrew@webrtc.org, tina.legrand@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/21299004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7009 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/build/common.gypi b/webrtc/build/common.gypi
index cbc398e..00bd4d4 100644
--- a/webrtc/build/common.gypi
+++ b/webrtc/build/common.gypi
@@ -112,6 +112,11 @@
     'mips_fpu%' : 1,
     'enable_android_opensl%': 1,
 
+    # Link-Time Optimizations
+    # Executes code generation at link-time instead of compile-time
+    # https://gcc.gnu.org/wiki/LinkTimeOptimization
+    'use_lto%': 0,
+
     'conditions': [
       ['build_with_chromium==1', {
         # Exclude pulse audio on Chromium since its prerequisites don't require