[x86] Teach my test updating script about another quirk of the printed

[x86] Teach my test updating script about another quirk of the printed
asm and port the mmx vector shuffle test to it.

Not thrilled with how it handles the stack manipulation logic, but I'm
much less bothered by that than I am by updating the test manually. =]
If anyone wants to teach the test checks management script about stack
adjustment patterns, that'd be cool too.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229268 91177308-0d34-0410-b5e6-96231b3b80d8