PR 628/rtems
* posix/src/killinfo.c, posix/src/pthreadkill.c, posix/src/ptimer1.c,
posix/src/sigaction.c, posix/src/sigaddset.c, posix/src/sigsuspend.c:
Signal set of 0 is supposed to return EINVAL. In addition
timer_create needed to return an error if the clock was not
CLOCK_REALTIME.