tests: address a warning from GCC 4.4

tests: address a warning from GCC 4.4

236. torture.at:465: testing Exploding the Stack Size with Alloca ...
../../../tests/torture.at:474: bison -o input.c input.y
../../../tests/torture.at:474: $CC $CFLAGS $CPPFLAGS $LDFLAGS -o input input.c $LIBS
stderr:
cc1: warnings being treated as errors
input.y: In function 'main':
input.y:60: error: 'status' may be used uninitialized in this function

* tests/torture.at (AT_DATA_STACK_TORTURE): Initial status to avoid
the previous error.