build: Move most of intl.m4 into gettext-runtime/intl/configure.ac.

build: Move most of intl.m4 into gettext-runtime/intl/configure.ac.

* gettext-runtime/m4/gettext.m4 (AM_GNU_GETTEXT): Don't invoke AM_INTL_SUBDIR.
* gettext-runtime/m4/intl.m4 (AM_INTL_SUBDIR, gt_GL_ATTRIBUTE): Remove macros.
(gt_INTL_SUBDIR_CORE): Test for uselocale.
* gnulib-local/modules/gettext-runtime-intl-misc (configure.ac): Ensure
LOCALENAME_ENHANCE_LOCALE_FUNCS initialization.
* autogen.sh (GNULIB_MODULES_LIBINTL): Add lib-symbol-visibility, localename.
* gettext-runtime/intl/configure.ac: Set WINDRES. Invoke gt_INTL_SUBDIR_CORE.
Set HAVE_POSIX_PRINTF, HAVE_ASPRINTF, HAVE_SNPRINTF, HAVE_WPRINTF,
HAVE_NEWLOCALE. Test for features.h, _snprintf, _snwprintf.
Set ENHANCE_LOCALE_FUNCS, WOE32DLL.