Clang: Do not flash issues pane when switching editor

Previously, when swichting to a file with errors, the Issues pane button
would flash.

Stop this for the clang code model issues as it is rather annoying since
the issues pane is updated for the current document.

Change-Id: I403a8b8cd0deef586c53769d0b646855a7fc9278
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/clangcodemodel/clangdiagnosticmanager.cpp

@@ -353,7 +353,7 @@ static void addTask(const ClangBackEnd::DiagnosticContainer &diagnostic, bool is
                           diagnostic.location.line,
                           Constants::TASK_CATEGORY_DIAGNOSTICS,
                           icon,
-                          /*addTextMark =*/ false));
+                          Task::NoOptions));
 }
 
 void ClangDiagnosticManager::clearTaskHubIssues()