Fix the problem in b/19277289 by avoiding calling walk_aliased_vdefs in O0 function.
tree4e7ed0e0ba69748477018d8e1dfc0767c83c28d1
drwxr-xr-x - gcc-4_6-mobile-vtable-security
drwxr-xr-x - gcc-4_6-mobile
drwxr-xr-x - gcc-4_6
drwxr-xr-x - gcc-4_6_2-mobile
drwxr-xr-x - gcc-4_6_3-mobile
drwxr-xr-x - gcc-4_7-integration
drwxr-xr-x - gcc-4_7-mobile-vtable-verification
drwxr-xr-x - gcc-4_7-mobile
drwxr-xr-x - gcc-4_7
drwxr-xr-x - gcc-4_8
drwxr-xr-x - gcc-4_9-mobile
drwxr-xr-x - gcc-4_9
drwxr-xr-x - integration
drwxr-xr-x - main