Check time arguments to pthread_timedjoin_np and pthread_clockjoin_np

The pthread_timedjoin_np and pthread_clockjoin_np functions do not
check that a valid time has been specified.  The documentation for
these functions in the glibc manual isn't sufficiently detailed to say
if they should, but consistency with POSIX functions such as
pthread_mutex_timedlock and pthread_cond_timedwait strongly indicates
that an EINVAL error is appropriate (even if there might be some
ambiguity about exactly where such a check should go in relation to
other checks for whether the thread exists, whether it's immediately
joinable, etc.).  Copy the logic for such a check used in
pthread_rwlock_common.c.

pthread_join_common had some logic calling valid_nanoseconds before
commit 9e92278ffa, "nptl: Remove
clockwait_tid"; I haven't checked exactly what cases that detected.

Tested for x86_64 and x86.

nptl/pthread_join_common.c

@@ -49,6 +49,12 @@ __pthread_clockjoin_ex (pthread_t threadid, void **thread_return,
     /* We cannot wait for the thread.  */
     return EINVAL;
 
+  /* Make sure the clock and time specified are valid.  */
+  if (abstime
+      && __glibc_unlikely (!futex_abstimed_supported_clockid (clockid)
+			   || ! valid_nanoseconds (abstime->tv_nsec)))
+    return EINVAL;
+
   struct pthread *self = THREAD_SELF;
   int result = 0;