Support MIPS64.

MIPS64 confusingly sets __mips__, but it's not a 32-bit platform. This
change updates the defines in base.h to recognise MIPS64 based on both
__mips__ and __LP64__ being defined.

BUG: 19665578

Change-Id: I6290b6def9f999a01b500c918d1488a22fd57460
1 file changed