AC_MSG_CHECKING(if struct __res_state _res is an extern)

AC_LINK_IFELSE([

#include <stdio.h>

#if HAVE_SYS_TYPES_H

# include <sys/types.h>

#endif

#include <netinet/in.h>

#include <arpa/nameser.h>

#include <resolv.h>

extern struct __res_state _res;

int main() { return 0; }

		],

		[AC_MSG_RESULT(yes)

		 AC_DEFINE(HAVE__RES_EXTERN, 1,

		    [Define if you have struct __res_state _res as an extern])

		],

		[ AC_MSG_RESULT(no) ]

)

#endif