src/config.in: shrink slightly

src/config.in: shrink slightly

* configure.in: Invoke the new gnulib macro gl_ASSERT_NO_GNULIB_TESTS.
This makes src/config.in a bit smaller, by removing identifiers
like GNULIB_TEST_MKTIME that Emacs does not need.
* m4/getopt.m4, m4/gnulib-common.m4, m4/include_next.m4:
* m4/multiarch.m4, m4/stddef_h.m4, m4/time_h.m4, m4/unistd_h.m4:
Sync from gnulib.  This removes a few more unnecessary symbols from
src/config.in, such as AA_APPLE_UNIVERSAL_BUILD and HAVE_STDDEF_H.
* configure, src/config.in: Regenerate.