x86emul/test: fix build after "x86emul: fix 3-operand IMUL"

Introduce the missing #define (and another one likely to be needed by
possible subsequent backports).

Signed-off-by: Jan Beulich <jbeulich@suse.com>

tools/tests/x86_emulator/test_x86_emulator.c

@@ -301,6 +301,9 @@ static struct x86_emulate_ops emulops = {
     .put_fpu    = emul_test_put_fpu,
 };
 
+#define EFLAGS_ALWAYS_SET (X86_EFLAGS_IF | X86_EFLAGS_MBS)
+#define EFLAGS_MASK (X86_EFLAGS_ARITH_MASK | EFLAGS_ALWAYS_SET)
+
 int main(int argc, char **argv)
 {
     struct x86_emulate_ctxt ctxt;