wined3d: Full surface DXTn copy.

Height * Pitch is not a valid way to calculate the surface size for
DXTn surfaces. Instead of messing with format specific formulas just
use the size stored in the destination surface.

dlls/wined3d/surface_gdi.c

@@ -555,8 +555,7 @@ IWineGDISurfaceImpl_Blt(IWineD3DSurface *iface,
             ret = WINED3DERR_WRONGTEXTUREFORMAT;
             goto release;
         }
-        TRACE("Fourcc->Fourcc copy)\n");
-        memcpy(dlock.pBits, slock.pBits, This->currentDesc.Height * dlock.Pitch);
+        memcpy(dlock.pBits, slock.pBits, This->resource.size);
         goto release;
     }