tst-longjmp_chk passes, tst-longjmp_chk2 fails but that is because
of some limitations of kernel signal delivery on sparc that I need
to fix, it has nothing to do with the longjmp_chk implementation.
(The problem with tst-longjmp_chk2 is that it tries to do a stack
fault SIGSEGV within a stack fault SIGSEGV , and the Linux kernel
will refuse to setup the signal stack and deliver the signal if the
register windows can't be written out to the stack first)
