Remove all trailing spaces

No real changes, just clean up sources by removing trailing spaces from
all the non-generated files.

This should hopefully avoid future commits mixing significant changes
with insignificant whitespace ones.

include/wx/gtk/dcmemory.h

@@ -39,7 +39,7 @@ public:
     virtual void DoGetSize( int *width, int *height ) const wxOVERRIDE;
     virtual wxBitmap DoGetAsBitmap(const wxRect *subrect) const wxOVERRIDE;
     virtual void* GetHandle() const wxOVERRIDE;
-    
+
     // overridden for wxMemoryDC Impl
     virtual void DoSelect(const wxBitmap& bitmap) wxOVERRIDE;