Include wx/app.h according to precompiled headers of wx/wx.h (with other minor cleaning).

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@38945 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/x11/dnd.cpp

@@ -21,10 +21,10 @@
 #ifndef WX_PRECOMP
     #include "wx/intl.h"
     #include "wx/log.h"
+    #include "wx/app.h"
 #endif
 
 #include "wx/window.h"
-#include "wx/app.h"
 #include "wx/gdicmn.h"
 #include "wx/utils.h"
 
@@ -184,7 +184,7 @@ wxDragResult wxDropSource::DoDragDrop( int WXUNUSED(flags) )
 
   UnregisterWindow();
 
-  g_blockEventsOnDrag = FALSE;
+  g_blockEventsOnDrag = false;
 
   return m_retValue;
 #endif