ProjectExplorer et al: Code cosmetics

Apply static 'pattern' for ToolChainManager, de-noise using code.

Change-Id: I196dc6f39dc2c61b1783aecad3faa0b23849e00a
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>

src/plugins/android/androidgdbserverkitinformation.h

@@ -33,11 +33,10 @@
 #include <projectexplorer/kitinformation.h>
 #include <projectexplorer/kitconfigwidget.h>
 
-QT_FORWARD_DECLARE_CLASS(QLabel);
-QT_FORWARD_DECLARE_CLASS(QPushButton);
-
-namespace ProjectExplorer {
-}
+QT_BEGIN_NAMESPACE
+class QLabel;
+class QPushButton;
+QT_END_NAMESPACE
 
 namespace Android {
 namespace Internal {