BUG/MINOR: resolvers: Use sc_need_room() to wait more room when dumping stats

It was a cut/paste typo during stream-interface to conn-stream
refactoring. sc_have_room() was used instead of sc_need_room().

This patch must be backported as far as 2.6.
diff --git a/src/resolvers.c b/src/resolvers.c
index 4b2e03e..ac0b015 100644
--- a/src/resolvers.c
+++ b/src/resolvers.c
@@ -2693,7 +2693,7 @@
 	return 1;
 
   full:
-	sc_have_room(sc);
+	sc_need_room(sc);
 	return 0;
 }