[X86] Mark pseudo instruction TEST8ri_NOEREX as hasSIdeEffects=0.

Also, add a case clause in X86InstrInfo::shouldScheduleAdjacent to enable
macro-fusion.

<rdar://problem/15680770>



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212747 91177308-0d34-0410-b5e6-96231b3b80d8