package/coreutils: fix cross-compile (add gl_cv_macro_MB_CUR_MAX_good=yes)

- add 'gl_cv_macro_MB_CUR_MAX_good=yes' to COREUTILS_CONF_ENV to fix
  cross-compile failure since bump to 9.3

Fixes:

  checking whether MB_CUR_MAX is correct... configure: error: in '.../build/coreutils-9.3':
  configure: error: cannot run test program while cross compiling
  See 'config.log' for more details

Reported-by: Christian Stewart <christian@aperture.us>
Link: https://lore.kernel.org/buildroot/CA+h8R2qSe6OepJMJr+KOUOAOqCRD9EX690Y+Yq4kx-M6x4uQBw@mail.gmail.com/
Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/coreutils/coreutils.mk

@@ -51,6 +51,7 @@ COREUTILS_CONF_ENV = ac_cv_c_restrict=no \
 	gl_cv_func_tzset_clobber=no \
 	gl_cv_func_working_mkstemp=yes \
 	gl_cv_func_working_utimes=yes \
+	gl_cv_macro_MB_CUR_MAX_good=yes \
 	gl_getline_needs_run_time_check=no \
 	gl_cv_have_proc_uptime=yes \
 	utils_cv_localtime_cache=no \