[x86] add tests for 8-bit multiply with constant; NFC

This is based on the existing file for 16-bit. We also already have 32-bit and 64-bit variants.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@347341 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed