PR ada/14538
* ada/5rosinte.adb: Remove fake mprotect() body.
* ada/5rosinte.ads: Add SA_SIGINFO.
* ada/5rtpopsp.adb: Rewrite to use new interface.
* ada/init.c: Reorder so the simple single OS conditional __rtems__
is tested before more complex ones which mix UNIX and embedded
systems in the conditional.