Debugger/gdb: Activate "target async" option in GUI.

Change-Id: Ic359d4af409993dfcc45ba95e6ab5e9287ef6d12
Reviewed-on: http://codereview.qt-project.org/5874
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Christian Kandeler <christian.kandeler@nokia.com>

src/plugins/debugger/gdb/gdboptionspage.cpp

@@ -140,7 +140,7 @@ QWidget *GdbOptionsPage::createPage(QWidget *parent)
     }
 
     // FIXME: Not fully working on the gdb side yet.
-    m_ui->checkBoxTargetAsync->hide();
+    //m_ui->checkBoxTargetAsync->hide();
 
     return w;
 }