intl: Use a locale.alias file only on glibc systems.

intl: Use a locale.alias file only on glibc systems.

On systems without glibc, it makes no sense if libintl supports locale name
aliases that the system's setlocale() does not support. Therefore better
disable the locale.alias processing on these platforms.

Also, stop installing locale.alias, because on systems without glibc we won't
read it any more, and on systems with glibc we need to use the preinstalled
one in /usr/share/locale/locale.alias.

* gettext-runtime/intl/localealias.c: Don't include relocatable.h.
(relocate, relocate2): Remove macros.
(LOCALE_ALIAS_PATH): Define a fallback.
(_nl_expand_alias): Simplify on systems without glibc.
(read_alias_file, extend_alias_table, alias_compare): Don't define on systems
without glibc.
* gettext-runtime/intl/Makefile.am (AM_CPPFLAGS): Don't set LOCALE_ALIAS_PATH.
(EXTRA_DIST): Remove locale.alias, ref-add.sin, ref-del.sin.
(MOSTLYCLEANFILES): Remove ref-add.sed, red-del.sed.
(ref-add.sed, ref-del.sed, install-data-aliasfile, installdirs-aliasfile,
uninstall-aliasfile): Remove rules.
* gettext-runtime/intl/locale.alias: Remove file.
* gettext-runtime/intl/ref-add.sin: Remove file.
* gettext-runtime/intl/ref-del.sin: Remove file.
* gettext-tools/src/Makefile.am (aliaspath): Remove variable.
(DEFS): Don't set LOCALE_ALIAS_PATH.
* PACKAGING: Don't mention locale.alias.