testsuite: Mark non-optimized variants as expensive

When not optimized for speed, the test for PR112344 takes several
seconds to execute on native x86_64, and 15 minutes on PRU target
simulator.  Thus mark those variants as expensive.  The -O2 variant
which originally triggered the PR is not expensive, hence it is
still run by default.

	PR middle-end/112344

gcc/testsuite/ChangeLog:

	* gcc.dg/torture/pr112344.c: Run non-optimized variants only
	if expensive tests are allowed.

Signed-off-by: Dimitar Dimitrov <dimitar@dinux.eu>

gcc/testsuite/gcc.dg/torture/pr112344.c

 /* { dg-do run } */
 /* { dg-require-effective-target int32plus } */
+/* { dg-skip-if "non-optimized code is too slow" { ! run_expensive_tests } { "*" } { "-O2" "-O3" } } */
 
 int
 main ()