pthread, pthread_sigmask, threadlib: port to Ubuntu 14.04 Problem reported by Assaf Gordon in: http://lists.gnu.org/archive/html/bug-gnulib/2014-09/msg00023.html Apparently Ubuntu is doing some fancy link-time optimization that doesn't work with -lpthread but does work with -pthread. Work around the bug by preferring -pthread to -lpthread. This change affects only LIBS, not CFLAGS, which is a little weird, but it works. * m4/pthread.m4 (gl_PTHREAD_CHECK): * m4/threadlib.m4 (gl_THREADLIB_BODY): Prefer -pthread to -lpthread. * m4/pthread_sigmask.m4 (gl_FUNC_PTHREAD_SIGMASK): Treat -pthread like -lpthread.