Fix multiple-selector warning

src/fmdb/FMDatabase.m

@@ -321,7 +321,7 @@ - (void)resultSetDidClose:(FMResultSet *)resultSet {
 - (void)clearCachedStatements {
     
     for (NSMutableSet *statements in [_cachedStatements objectEnumerator]) {
-        [statements makeObjectsPerformSelector:@selector(close)];
+        for (FMStatement *statement in statements.allObjects) [statement close];
     }
     
     [_cachedStatements removeAllObjects];