_mesa_swizzle_ubyte_image: Only use single swizzle_copy call when strides match.

This fixes texture data corruption with glTexSubimage (and probably glTexImage
under some circumstances) with the texstore swizzle path.

src/mesa/main/texstore.c

@@ -808,7 +808,8 @@ _mesa_swizzle_ubyte_image(GLcontext *ctx,
 
 /*    _mesa_printf("map %d %d %d %d\n", map[0], map[1], map[2], map[3]);  */
 
-   if (srcRowStride == srcWidth * srcComponents &&
+   if (srcRowStride == dstRowStride &&
+       srcRowStride == srcWidth * srcComponents &&
        dimensions < 3) {
       /* 1 and 2D images only */
       GLubyte *dstImage = (GLubyte *) dstAddr