Remove unused NACL_ARCH_CPU_* #defines from portability.h
Remove unused NACL_ARCH_CPU_* #defines from portability.h

NACL_WCHAR_T_IS_UNSIGNED is unused too.

BUG=none
TEST=trybots

Review URL: https://chromiumcodereview.appspot.com/10928187

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@9736 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

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