* POSIX include files merged into newlib. This resulted in
some definitions moving to other files and thus some secondary
effects in RTEMS source code.
* include/confdefs.h: Replaced include of <sys/siginfo.h> with
<signal.h> since that file no longer exists.
* include/confdefs.h: Modified code that accounts for initialization
task/threads with greater than minimum stack sizes so it would
compile even if optional APIs are disabled.
