target/i386/tcg: ignore V3 in 32-bit mode

From the manual: "In 64-bit mode all 4 bits may be used. [...]
In 32-bit and 16-bit modes bit 6 must be 1 (if bit 6 is not 1, the
2-byte VEX version will generate LDS instruction and the 3-byte VEX
version will ignore this bit)."

Cc: qemu-stable@nongnu.org
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 0db1b556e4bcd7a51f222cda9e14850f88fe3f88)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

target/i386/tcg/decode-new.c.inc

@@ -2665,7 +2665,7 @@ static void disas_insn(DisasContext *s, CPUState *cpu)
                     goto unknown_op;
                 }
             }
-            s->vex_v = (~vex3 >> 3) & 0xf;
+            s->vex_v = (~vex3 >> 3) & (CODE64(s) ? 15 : 7);
             s->vex_l = (vex3 >> 2) & 1;
             s->prefix |= pp_prefix[vex3 & 3] | PREFIX_VEX;
         }