start to clean up buildMI calls in mips fast-isel

Summary: Merge branch 'master' into 1758_6

Test Plan:
No functionality change. Run "make check" and run test-suite.
Because our servers are not yet running again I have not yet run test-suite.
I will further review myself before submission.

Reviewers: dsanders

Reviewed By: dsanders

Differential Revision: http://reviews.llvm.org/D3819