gdiplus: Add GdipSaveAdd stub.

dlls/gdiplus/gdiplus.spec

diff --git a/dlls/gdiplus/gdiplus.spec b/dlls/gdiplus/gdiplus.spec
index 01e8dd7..7d6c51f 100644
--- a/dlls/gdiplus/gdiplus.spec
+++ b/dlls/gdiplus/gdiplus.spec
@@ -471,7 +471,7 @@
 471 stdcall GdipRotatePenTransform(ptr float long)
 472 stdcall GdipRotateTextureTransform(ptr float long)
 473 stdcall GdipRotateWorldTransform(ptr float long)
-474 stub GdipSaveAdd
+474 stdcall GdipSaveAdd(ptr ptr)
 475 stub GdipSaveAddImage
 476 stdcall GdipSaveGraphics(ptr ptr)
 477 stdcall GdipSaveImageToFile(ptr ptr ptr ptr)

dlls/gdiplus/image.c

diff --git a/dlls/gdiplus/image.c b/dlls/gdiplus/image.c
index d1affae..fe56377 100644
--- a/dlls/gdiplus/image.c
+++ b/dlls/gdiplus/image.c
@@ -3459,6 +3459,15 @@
 }
 
 /*****************************************************************************
+ * GdipSaveAdd [GDIPLUS.@]
+ */
+GpStatus WINGDIPAPI GdipSaveAdd(GpImage *image, GDIPCONST EncoderParameters *params)
+{
+    FIXME("(%p,%p): stub\n", image, params);
+    return Ok;
+}
+
+/*****************************************************************************
  * GdipGetImagePalette [GDIPLUS.@]
  */
 GpStatus WINGDIPAPI GdipGetImagePalette(GpImage *image, ColorPalette *palette, INT size)