We have multiple tests that copy & paste the same logic for disabling the
fortification output. Let's unify this in the test-skeleton instead.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
If longjmp restores the stack frame to an address which is beyond
the stack frame at the time of the longjmp call it would install
an uninitialized stack frame. If compiled with _FORTIFY_SOURCE
defined, longjmp will now bail out in this situation.
