linux: set -fvisiblility-inlines-hidden when building

This matches the Mac and shaves a surprising 300kb off the binary.

Review URL: http://codereview.chromium.org/402003

git-svn-id: http://src.chromium.org/svn/trunk/src/build@32185 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

common.gypi

@@ -508,6 +508,9 @@
         'cflags_cc': [
           '-fno-rtti',
           '-fno-threadsafe-statics',
+          # Make inline functions have hidden visiblity by default.
+          # Surprisingly, not covered by -fvisibility=hidden.
+          '-fvisibility-inlines-hidden',
         ],
         'ldflags': [
           '-pthread',