c32rtomb: Add a sanity check, working around Solaris 11 OmniOS.
* m4/c32rtomb.m4 (gl_CHECK_FUNC_C32RTOMB): New macro, extracted from
gl_FUNC_C32RTOMB.
(gl_C32RTOMB_SANITYCHECK): New macro.
(gl_FUNC_C32RTOMB): Require gl_CHECK_FUNC_C32RTOMB and
gl_C32RTOMB_SANITYCHECK. If HAVE_WORKING_C32RTOMB is 0, set
REPLACE_C32RTOMB.
* lib/c32rtomb.c (c32rtomb): Together with HAVE_WORKING_MBRTOC32, test
also HAVE_WORKING_C32RTOMB.
* m4/mbrtoc32.m4 (gl_PREREQ_MBRTOC32): Require gl_C32RTOMB_SANITYCHECK.
* lib/mbrtoc32.c (mbrtoc32): Together with HAVE_WORKING_MBRTOC32, test
also HAVE_WORKING_C32RTOMB.
* modules/mbrtoc32 (Files): Add m4/c32rtomb.m4.
* lib/btoc32.c (btoc32): Together with HAVE_WORKING_MBRTOC32, test also
HAVE_WORKING_C32RTOMB.
* lib/mbsrtoc32s.c: Together with HAVE_WORKING_MBRTOC32, test also
HAVE_WORKING_C32RTOMB.
* lib/mbsnrtoc32s.c: Together with HAVE_WORKING_MBRTOC32, test also
HAVE_WORKING_C32RTOMB.
* lib/c32tob.c (c32tob): Together with HAVE_WORKING_MBRTOC32, test also
HAVE_WORKING_C32RTOMB.
* modules/c32tob (Files): Add m4/c32rtomb.m4.
(configure.ac): Require gl_C32RTOMB_SANITYCHECK.
* lib/c32srtombs.c: Together with HAVE_WORKING_MBRTOC32, test also
HAVE_WORKING_C32RTOMB.
* lib/c32snrtombs.c: Together with HAVE_WORKING_MBRTOC32, test also
HAVE_WORKING_C32RTOMB.
* lib/c32to-impl.h (FUNC): Together with HAVE_WORKING_MBRTOC32, test
also HAVE_WORKING_C32RTOMB.
* modules/c32tolower (Files): Add m4/c32rtomb.m4.
(configure.ac): Require gl_C32RTOMB_SANITYCHECK.
* modules/c32toupper (Files): Add m4/c32rtomb.m4.
(configure.ac): Require gl_C32RTOMB_SANITYCHECK.
* lib/c32width.c (c32width): Together with HAVE_WORKING_MBRTOC32, test
also HAVE_WORKING_C32RTOMB.
* modules/c32width (Files): Add m4/c32rtomb.m4.
(configure.ac): Require gl_C32RTOMB_SANITYCHECK.