build: Simplify the use of gnulib in libasprintf.
* autogen.sh (GNULIB_MODULES_LIBASPRINTF): Add vasnprintf. Remove attribute,
errno, verify, xsize.
Pass option '--source-base=gnulib-lib' instead of
'--source-base=. --makefile-name=Makefile.gnulib'.
Don't create any gettext-runtime/libasprintf/gnulib-m4/*.m4 file through simple
copy.
* gettext-runtime/libasprintf/printf-args.c: Remove file.
* gettext-runtime/libasprintf/printf-args.h: Remove file.
* gettext-runtime/libasprintf/printf-parse.c: Remove file.
* gettext-runtime/libasprintf/printf-parse.h: Remove file.
* gettext-runtime/libasprintf/vasnprintf.c: Remove file.
* gettext-runtime/libasprintf/vasnprintf.h: Remove file.
* gettext-runtime/libasprintf/lib-asprintf.c: Don't include printf-args.c,
printf-parse.c, vasnprintf.c, asnprintf.c.
(STATIC): Remove macro.
* gettext-runtime/libasprintf/configure.ac: Hide undesired symbols from the
global namespace.
(AC_CONFIG_FILES): Add gnulib-lib/Makefile.
* gettext-runtime/libasprintf/Makefile.am: Don't include Makefile.gnulib.
(SUBDIRS, AM_CPPFLAGS): New variable.
(libasprintf_la_SOURCES, lib_asprintf_EXTRASOURCES): Remove files that are now
in gnulib-lib/.
(LIBASPRINTF_EXPORTED_SYMBOLS_REGEX): New variable.
(libasprintf_la_LDFLAGS): Use it.
(libasprintf.la): Link with gnulib-lib/libgnu.la.
* Makefile.am (distcheck-hook): Don't check the files in
gettext-runtime/libasprintf/.
