Remove unneeded class prefix that is rejected by gcc
Remove unneeded class prefix that is rejected by gcc

I found this when trying to compile win/mutex_impl.cc with MinGW's gcc.

BUG=http://code.google.com/p/nativeclient/issues/detail?id=1283
TEST=trybots

Review URL: http://codereview.chromium.org/5968011

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@4048 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

nacl-webkit/native_client,nacl-webkit/native_client,sbc100/native_client,sbc100/native_client,nacl-webkit/native_client,sbc100/native_client,sbc100/native_client,nacl-webkit/native_client,sbc100/native_client,sbc100/native_client,nacl-webkit/native_client