gettext CVS bug with __argz_*

[Eric Blake]

I got this failure when trying to compile CVS gettext on cygwin:

 gcc -c -DLOCALEDIR=\"/usr/local/share/locale\" -
DLOCALE_ALIAS_PATH=\"/usr/local/share/locale\" -DLIBDIR=\"/usr/local/lib\" -
DBUILDING_LIBINTL -DBUILDING_DLL -DIN_LIBINTL -DENABLE_RELOCATABLE=1 -
DIN_LIBRARY -DINSTALLDIR=\"/usr/local/lib\" -DNO_XMALLOC -
Dset_relocation_prefix=libintl_set_relocation_prefix -
Drelocate=libintl_relocate -DDEPENDS_ON_LIBICONV=1 -DHAVE_CONFIG_H -I. -I. -
I.. -g2 -Wall -Werror ./l10nflist.c  -DPIC -o .libs/l10nflist.o
./l10nflist.c: In function `_nl_make_l10nflist':
./l10nflist.c:210: warning: implicit declaration of function `__argz_stringify'
./l10nflist.c:267: warning: implicit declaration of function `__argz_count'
./l10nflist.c:314: warning: implicit declaration of function `__argz_next'
./l10nflist.c:314: warning: assignment makes pointer from integer without a cast
make[3]: *** [l10nflist.lo] Error 1

I traced it to the fact that gettext-runtime/m4/gettext.m4 does
AC_CHECK_FUNCS([__argz_stringify]), but not AC_CHECK_FUNCS([argz_stringify]).
Cygwin exports both names as aliases of the same function, but the header
/usr/include/argz.h defines ONLY argz_stringify.  Therefore, using
a link-only check for __argz_{stringify,count,next} without also checking
for a declaration of {__,}argz_{stringify,count,next} leads to compilation
failure.

-- 
Eric Blake