* gnulib/m4/multiarch.m4: New file.
* gnulib/m4/hostent.m4: New file.
* gnulib/m4/servent.m4: New file.
* .x-sc_prohibit_gethostby: Exempt all gnulib/m4/* files, so
hostent.m4's uses of gethostbyname and gethostbyaddr do not
trigger a "make syntax-check" failure.