Reland "[mips] Guard traps for microMIPS correctly"

This is part of fixing the instruction predicates for MIPS.

Reviewers: atanasyan, abeserminji

Differential Revision: https://reviews.llvm.org/D44212


This patch relands r327409, hopefully without the problematic part of the
tests that cause FileCheck to assert on the windows expensive checks bot.

llvm-svn: 330741