Cache SRV records.

Inpsired by a patch from Jeremy Allison, but completely re-rolled
by srk. All bugs are mine.
diff --git a/src/auth.c b/src/auth.c
index 24ef0d7..7446580 100644
--- a/src/auth.c
+++ b/src/auth.c
@@ -129,7 +129,7 @@
 
   for (q = ntohs(header->qdcount); q != 0; q--)
     {
-      unsigned short flag = 0;
+      unsigned int flag = 0;
       int found = 0;
       int cname_wildcard = 0;