Replace open() with exec() in order to prevent the high cpu occupancy.

search-ukcc-plugin/search.cpp

@@ -756,10 +756,13 @@ void Search::setupConnection()
 
 void Search::onBtnAddBlockFolderClicked()
 {
-    m_blockDirDialog->open();
+//    m_blockDirDialog->open();
+    m_blockDirDialog->exec();
 }
 
 void Search::onAddSearchDirBtnClicked()
 {
-    m_searchDirDialog->open();
+    //open()会导致cpu占用拉满
+//    m_searchDirDialog->open();
+    m_searchDirDialog->exec();
 }