Make calling card buddy map a flat_hash_map for increased find performance

indra/newview/llcallingcard.h

@@ -107,7 +107,7 @@ public:
 
 	// add or remove agents from buddy list. Each method takes a set
 	// of buddies and returns how many were actually added or removed.
-	typedef std::map<LLUUID, LLRelationship*> buddy_map_t;
+	typedef absl::flat_hash_map<LLUUID, LLRelationship*> buddy_map_t;
 
 	S32 addBuddyList(const buddy_map_t& buddies);
 	//S32 removeBuddyList(const buddy_list_t& exes);