type tweak

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@2917 d0543943-73ff-0310-b7d9-9358b9ac24b2

libs/libdingaling/src/libdingaling.c

@@ -464,7 +464,7 @@ static int on_presence(void *user_data, ikspak *pak)
 
 	if (resource) {
 		for (x = 0; x < strlen(resource); x++) {
-			resource[x] = tolower(resource[x]);
+			resource[x] = (char)tolower((int)resource[x]);
 		}
 	}