fixing expected return value for loop-freeness test

Author: Remi Delmas

regression/contracts/loop-freeness-check/test.desc

@@ -5,7 +5,7 @@ main.c
 ^Invariant check failed$
 ^Condition: is_loop_free\(goto_program\)$
 ^Reason: Loops remain in function 'foo', assigns clause checking instrumentation cannot be applied\.$
-^EXIT=134$
+^EXIT=(127|134)$
 ^SIGNAL=0$
 --
 --