[x86] Add an explicit SSE3 run to this test and flesh out a bunch of
missing specific checks.

While there is a lot of redundancy here where all-but-one mode use the
same code generation, I'd rather have each variant spelled out and
checked so that readers aren't misled by an omission in the test suite.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217765 91177308-0d34-0410-b5e6-96231b3b80d8