[x86] add 32-bit RUN for tests and test with opaque constants; NFC

The opaque constant test is reduced from a Chrome file that
infinite-looped with rL347917.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@348705 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed