[x86] Merge still more combine tests into the common file. These at
least seem *slightly* more interesting test wise, although given how
spotily we actually combine anything, I remain somewhat suspicious.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218861 91177308-0d34-0410-b5e6-96231b3b80d8