Xorg libraries that use Xmalloc need to know if malloc(0) returns NULL or not,
and as this is a runtime test it can't be checked for. Previously
xorg-lib-common declared that malloc(0) did return NULL, but this isn't true for
eglibc (only uclibc).
Instead, use libc-specific overrides to pass the relevant option.
(ideally the check would use the autoconf cache so this can be stored in the site files)
Signed-off-by: Ross Burton <ross.burton@intel.com> Signed-off-by: Saul Wold <sgw@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
