Land gyp change to remove -Os from C++ flags if it exists on Linux.

Review URL: http://codereview.chromium.org/439014

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3347 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

tools/gyp/v8.gyp

@@ -81,6 +81,7 @@
           ['OS=="linux"', {
             'cflags!': [
               '-O2',
+              '-Os',
             ],
             'cflags': [
               '-fomit-frame-pointer',