getopt-gnu: avoid crash in glibc getopt Use of "W;" in an option string may be rare, but we might as well avoid crashing on it. * m4/getopt.m4 (gl_GETOPT_CHECK_HEADRS): Detect the problem. * tests/test-getopt.h (test_getopt): Enhance test. * tests/test-getopt_long.h (test_getopt_long): Likewise. * doc/posix-functions/getopt.texi (getopt): Document it. * doc/glibc-functions/getopt_long.texi (getopt_long): Likewise. * doc/glibc-functions/getopt_long_only.texi (getopt_long_only): Likewise. Signed-off-by: Eric Blake <eblake@redhat.com>