Add header file with missing wxScopedPtr declaration

wxScopedPtr is referred in wxSVGFileDCImpl declaration, but corresponding
header file is not explicitly included. This can break the compilation if
wxScopedPtr declaration is not included by chance by another module (e.g.
is taken from translation.h but it is not effective when wxUSE_INTL==0).

include/wx/dcsvg.h

@@ -16,6 +16,8 @@
 
 #if wxUSE_SVG
 
+#include "wx/scopedptr.h"
+
 #define wxSVGVersion wxT("v0101")
 
 class WXDLLIMPEXP_FWD_BASE wxFileOutputStream;