Add some missing includes.

Change-Id: Ieec623c06bc32ec78334f628af25b00c2bccd2e7
diff --git a/libc/netbsd/resolv/res_debug.c b/libc/netbsd/resolv/res_debug.c
index 721e015..46e583b 100644
--- a/libc/netbsd/resolv/res_debug.c
+++ b/libc/netbsd/resolv/res_debug.c
@@ -123,6 +123,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <strings.h>
 #include <time.h>