Ensure that HAVE_* variables are set to 1 before they are set to 0. * m4/fdopendir.m4 (gl_FUNC_FDOPENDIR): Require gl_DIRENT_H_DEFAULTS. * m4/inet_ntop.m4 (gl_FUNC_INET_NTOP): Require gl_ARPA_INET_H_DEFAULTS. * m4/inet_pton.m4 (gl_FUNC_INET_PTON): Likewise. * m4/pthread_sigmask.m4 (gl_FUNC_PTHREAD_SIGMASK): Require gl_SIGNAL_H_DEFAULTS.