target/i386: REPZ and REPNZ are mutually exclusive

The later prefix wins if both are present, make it show in s->prefix too.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

target/i386/tcg/translate.c

@@ -4733,9 +4733,11 @@ static target_ulong disas_insn(DisasContext *s, CPUState *cpu)
     switch (b) {
     case 0xf3:
         prefixes |= PREFIX_REPZ;
+        prefixes &= ~PREFIX_REPNZ;
         goto next_byte;
     case 0xf2:
         prefixes |= PREFIX_REPNZ;
+        prefixes &= ~PREFIX_REPZ;
         goto next_byte;
     case 0xf0:
         prefixes |= PREFIX_LOCK;