check_c_source_compiles("
#ifndef __NetBSD__
# define _XOPEN_SOURCE 600
#endif
#include <stdlib.h>
int
main(int argc, char *argv[])
{
	long double ld;
	char *ep = NULL;
	char *foo = \"1234\";

	ld = strtold(foo, &ep);
	return (ld != 1234.0);
}
" _MK_HAVE_STRTOLD)