target/i386: Generate an illegal opcode exception on cmp instructions with lock prefix

target/i386: Generate an illegal opcode exception on cmp instructions with lock prefix

target/i386: As specified by Intel Manual Vol2 3-180, cmp instructions
are not allowed to have lock prefix and a `UD` should be raised. Without
this patch, s1->T0 will be uninitialized and used in the case OP_CMPL.

Signed-off-by: Ziqiao Kong <ziqiaokong@gmail.com>
Message-ID: <20240215095015.570748-2-ziqiaokong@gmail.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 99d0dcd7f102c07a510200d768cae65e5db25d23)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>