[dev.ssa] cmd/compile: MOVBconst might also clobber flags

It gets rewritten to an xor by the linker also.

Change-Id: Iae35130325d41bd1a09b7e971190cae6f4e17fac
Reviewed-on: https://go-review.googlesource.com/20058Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/internal/gc/ssa.go

@@ -4649,7 +4649,7 @@ func (s *genState) markMoves(b *ssa.Block) {
 	}
 	for i := len(b.Values) - 1; i >= 0; i-- {
 		v := b.Values[i]
-		if flive && (v.Op == ssa.OpAMD64MOVWconst || v.Op == ssa.OpAMD64MOVLconst || v.Op == ssa.OpAMD64MOVQconst) {
+		if flive && (v.Op == ssa.OpAMD64MOVBconst || v.Op == ssa.OpAMD64MOVWconst || v.Op == ssa.OpAMD64MOVLconst || v.Op == ssa.OpAMD64MOVQconst) {
 			// The "mark" is any non-nil Aux value.
 			v.Aux = v
 		}