* sysdeps/pthread/posix-timer.h (struct timer_node): Add creator_pid.
* sysdeps/pthread/timer_create.c: Fill in creator_pid.
* sysdeps/pthread/timer_routines.c (thread_expire_timer): Send signal
with sigqueueinfo is this system call is available.
* sysdeps/pthread/timer_create.c (timer_create): Allow
CLOCK_CPUTIME if _POSIX_CPUTIME is defined.