windows/direct2d: fix ID2D1RenderTarget::GetPixelFormat() and ID2D1Re…

…nderTarget::GetSize() typedefs in MinGW-w64 ABI workaround

MinGW-w64 recently added manual workarounds directly into the class via overloads that make existing Direct2D code source-compatible. However, that exposed an error in my definition of the typedefs I was using in my own workaround: both of these methods are const, even in MSVC, but I neglected to include the const qualifier. I'm not sure how this code compiled in the past, but now the overload resolution engine finds no match.

I want to remain compatible with versions of MinGW-w64 old enough to not have their fix, so our fix remains.

Fixes #446.

windows/colordialog.cpp

@@ -314,7 +314,7 @@ static void drawGrid(ID2D1RenderTarget *rt, D2D1_RECT_F *fillRect)
 	pformat = rt->GetPixelFormat();
 #else
 	{
-		typedef D2D1_PIXEL_FORMAT *(__stdcall ID2D1RenderTarget::* GetPixelFormatF)(D2D1_PIXEL_FORMAT *);
+		typedef D2D1_PIXEL_FORMAT *(__stdcall ID2D1RenderTarget::* GetPixelFormatF)(D2D1_PIXEL_FORMAT *) const;
 		GetPixelFormatF gpf;
 
 		gpf = (GetPixelFormatF) (&(rt->GetPixelFormat));

windows/winutil.cpp

@@ -144,7 +144,7 @@ D2D1_SIZE_F realGetSize(ID2D1RenderTarget *rt)
 	return rt->GetSize();
 #else
 	D2D1_SIZE_F size;
-	typedef D2D1_SIZE_F *(__stdcall ID2D1RenderTarget::* GetSizeF)(D2D1_SIZE_F *);
+	typedef D2D1_SIZE_F *(__stdcall ID2D1RenderTarget::* GetSizeF)(D2D1_SIZE_F *) const;
 	GetSizeF gs;
 
 	gs = (GetSizeF) (&(rt->GetSize));