Last change for mips16 prolog/epilog cleanup and optimization.

Last change for mips16 prolog/epilog cleanup and optimization.
Some tiny cosmetic code changes to follow. Because of the wide
ranging nature of the patch a full 24 test cycle was needed to
check against regression. This was the smallest patch I could
make to progress from the earlier ones in the series.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197350 91177308-0d34-0410-b5e6-96231b3b80d8