Move wxUSE_ENH_METAFILE check inside wx/msw/enhmeta.h itself

This is more consistent with the other headers, which are safe to
include even when the corresponding feature is turned off.

Also remove the now redundant wxUSE_ENH_METAFILE checks in the source
code including this header.

See https://github.com/wxWidgets/wxWidgets/pull/951

include/wx/msw/enhmeta.h

@@ -11,6 +11,10 @@
 #ifndef _WX_MSW_ENHMETA_H_
 #define _WX_MSW_ENHMETA_H_
 
+#include "wx/defs.h"
+
+#if wxUSE_ENH_METAFILE
+
 #include "wx/dc.h"
 #include "wx/gdiobj.h"
 
@@ -192,4 +196,6 @@ protected:
 
 #endif // wxUSE_DATAOBJ
 
+#endif // wxUSE_ENH_METAFILE
+
 #endif // _WX_MSW_ENHMETA_H_

src/common/graphcmn.cpp

@@ -32,10 +32,8 @@
 #endif
 
 #ifdef __WXMSW__
-#if wxUSE_ENH_METAFILE
     #include "wx/msw/enhmeta.h"
 #endif
-#endif
 
 #include "wx/private/graphics.h"
 

src/generic/graphicc.cpp

@@ -41,7 +41,7 @@ bool wxCairoInit();
 #include "wx/private/graphics.h"
 #include "wx/rawbmp.h"
 #include "wx/vector.h"
-#if defined(__WXMSW__) && wxUSE_ENH_METAFILE
+#ifdef __WXMSW__
     #include "wx/msw/enhmeta.h"
 #endif
 

src/msw/graphics.cpp

@@ -42,9 +42,7 @@
 #include "wx/private/graphics.h"
 #include "wx/msw/wrapgdip.h"
 #include "wx/msw/dc.h"
-#if wxUSE_ENH_METAFILE
-    #include "wx/msw/enhmeta.h"
-#endif
+#include "wx/msw/enhmeta.h"
 #include "wx/dcgraph.h"
 #include "wx/rawbmp.h"
 

src/msw/printwin.cpp

@@ -48,9 +48,8 @@
 #include "wx/msw/printdlg.h"
 #include "wx/msw/private.h"
 #include "wx/msw/dcprint.h"
-#if wxUSE_ENH_METAFILE
-    #include "wx/msw/enhmeta.h"
-#endif
+#include "wx/msw/enhmeta.h"
+
 #include <stdlib.h>
 
 // ---------------------------------------------------------------------------