Merge argp, getopt, xalloc changes from gnulib.
* bootstrap (gnulib_modules): Add xalloc-die.
Remove code to test for patches; we don't have patches now.
+ Set LC_ALL=C so that file names sort consistently.
+ Prefer the gnulib copies of gettext.m4, glibc21.m4,
+ lib-ld.m4, lib-prefix.m4, po.m4 too.
+
* patches/getopt.diff: Remove; gnulib now works unpatched.
* configure.ac (_getopt_long_only_r): Remove check.
gl_ARGP now does this for us.