pthread_sigmask, timer-time: use gl_THREADLIB only if needed Without this fix, Emacs would sometimes call sigprocmask instead of pthread_sigmask, which is a no-no in multithreaded applications. Problem reported by Jorgen Schaefer in <http://bugs.gnu.org/17561>. * m4/pthread_sigmask.m4 (gl_FUNC_PTHREAD_SIGMASK): Suppress check for pthread_sigmask working without -lpthread if the application always links with -lpthread. Do not link with $LIBMULTITHREAD if gl_THREADLIB is not defined. * m4/timer_time.m4 (gl_TIMER_TIME): Require gl_THREADLIB only if it is defined. Do not append $LIBMULTITHREAD to LIB_TIMER_TIME if gl_THREADLIB is not defined.