On Alpha Linux, the mmap'd stack needs to be made executable because setjmp/signal seem to put machine instructions on the stack.  This fix is contributed by gatgul@voicenet.com (Uncle George).
On Alpha Linux, the mmap'd stack needs to be made executable because
setjmp/signal seem to put machine instructions on the stack.  This
fix is contributed by gatgul@voicenet.com (Uncle George).

makotokato/nsprpub,makotokato/nsprpub,makotokato/nsprpub,makotokato/nsprpub,makotokato/nsprpub