EXT-7668 FIXED prohibited deselecting a single selected item w/o using CTRL

Reviewed by Vadim Savchuk at https://codereview.productengine.com/secondlife/r/746/

--HG--
branch : product-engine

indra/llui/llflatlistview.cpp

@@ -608,8 +608,14 @@ void LLFlatListView::onItemMouseClick(item_pair_t* item_pair, MASK mask)
 		return;
 	}
 
-	if (!(mask & MASK_CONTROL) || !mMultipleSelection) resetSelection();
-	selectItemPair(item_pair, select_item);
+	//no need to do additional commit on selection reset
+	if (!(mask & MASK_CONTROL) || !mMultipleSelection) resetSelection(true);
+
+	//only CTRL usage allows to deselect an item, usual clicking on an item cannot deselect it
+	if (mask & MASK_CONTROL)
+		selectItemPair(item_pair, select_item);
+	else
+		selectItemPair(item_pair, true);
 }
 
 void LLFlatListView::onItemRightMouseClick(item_pair_t* item_pair, MASK mask)