nis_rpcent: don't leak resultbuf from yp_first(..)/yp_next(..)

If the buffer couldn't be adequately resized to accomodate an additional "\n",
it would leak resultbuf by breaking from the loop early

MFC after: 2 weeks
Reported by: Coverity
CID: 1016702
Sponsored by: EMC / Isilon Storage Division

lib/libc/rpc/getrpcent.c

@@ -511,6 +511,7 @@ nis_rpcent(void *retval, void *mdata, va_list ap)
 		    sizeof(char *)) {
 			*errnop = ERANGE;
 			rv = NS_RETURN;
+			free(resultbuf);
 			break;
 		}
 
@@ -520,6 +521,7 @@ nis_rpcent(void *retval, void *mdata, va_list ap)
 		if (aliases_size < 1) {
 			*errnop = ERANGE;
 			rv = NS_RETURN;
+			free(resultbuf);
 			break;
 		}