Added version check

Added version check, to only include the new Searchbar icon for Users
running Qt 5+

cockatrice/src/tab_deck_editor.cpp

@@ -51,7 +51,9 @@ TabDeckEditor::TabDeckEditor(TabSupervisor *_tabSupervisor, QWidget *parent)
     aClearSearch->setIcon(QIcon(":/resources/icon_clearsearch.svg"));
     connect(aClearSearch, SIGNAL(triggered()), this, SLOT(actClearSearch()));
     searchEdit = new SearchLineEdit;
+#if QT_VERSION >= 0x050000
     searchEdit->addAction(QIcon(":/resources/icon_search_black.svg"), QLineEdit::LeadingPosition);
+#endif
     searchEdit->setObjectName("searchEdit");
     
     setFocusProxy(searchEdit);