Add a late SSEDomainFix pass that twiddles SSE instructions to avoid domain crossings.

Add a late SSEDomainFix pass that twiddles SSE instructions to avoid domain crossings.

This is work in progress. So far, SSE execution domain tables are added to
X86InstrInfo, and a skeleton pass is enabled with -sse-domain-fix.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@99345 91177308-0d34-0410-b5e6-96231b3b80d8