target/rx: Fix compiler errors for build with sanitizers

target/rx: Fix compiler errors for build with sanitizers

gcc (Debian 10.2.1-6) 10.2.1 20210110 aborts builds with enabled sanitizers:

../../../target/rx/op_helper.c: In function ‘helper_scmpu’:
../../../target/rx/op_helper.c:213:24: error: ‘tmp1’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  213 |     env->psw_c = (tmp0 >= tmp1);
      |                  ~~~~~~^~~~~~~~
../../../target/rx/op_helper.c:213:24: error: ‘tmp0’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
../../../target/rx/op_helper.c: In function ‘helper_suntil’:
../../../target/rx/op_helper.c:299:23: error: ‘tmp’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  299 |     env->psw_c = (tmp <= env->regs[2]);
      |                  ~~~~~^~~~~~~~~~~~~~~~
../../../target/rx/op_helper.c: In function ‘helper_swhile’:
../../../target/rx/op_helper.c:318:23: error: ‘tmp’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  318 |     env->psw_c = (tmp <= env->regs[2]);
      |                  ~~~~~^~~~~~~~~~~~~~~~

Rewriting the code fixes those errors.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20210128172127.46041-1-sw@weilnetz.de>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>