Fix for a memory leak ( via https://github.com/ccgus/fmdb/issues/615 )

src/fmdb/FMResultSet.m

@@ -61,7 +61,7 @@ - (void)close {
     // we don't need this anymore... (i think)
     //[_parentDB setInUse:NO];
     [_parentDB resultSetDidClose:self];
-    _parentDB = nil;
+    [self setParentDB:nil];
 }
 
 - (int)columnCount {