don't claim support for resolv.h APIs that aren't supported

the value 19991006 for __RES implies availability of res_ninit and
related functions that take a resolver state argument; these are not
supported since our resolver is stateless. instead claim support for
just the older API by defining __RES to 19960801.

based on patch by Dmitrij D. Czarkoff.

include/resolv.h

@@ -61,7 +61,7 @@ typedef struct __res_state {
 	} _u;
 } *res_state;
 
-#define	__RES	19991006
+#define	__RES	19960801
 
 #ifndef _PATH_RESCONF
 #define _PATH_RESCONF        "/etc/resolv.conf"