dds: Write the palette in the native endian form

This fixes the palette on big endian, broken (or, differing from
little endian) since 57214b2f.
Signed-off-by: Martin Storsjö <martin@martin.st>

libavcodec/dds.c

@@ -653,14 +653,16 @@ static int dds_decode(AVCodecContext *avctx, void *data,
 
         if (ctx->paletted) {
             int i;
-            uint8_t *p = frame->data[1];
+            uint32_t *p = (uint32_t*) frame->data[1];
 
             /* Use the first 1024 bytes as palette, then copy the rest. */
             for (i = 0; i < 256; i++) {
-                p[i * 4 + 2] = bytestream2_get_byte(gbc);
-                p[i * 4 + 1] = bytestream2_get_byte(gbc);
-                p[i * 4 + 0] = bytestream2_get_byte(gbc);
-                p[i * 4 + 3] = bytestream2_get_byte(gbc);
+                uint32_t rgba = 0;
+                rgba |= bytestream2_get_byte(gbc) << 16;
+                rgba |= bytestream2_get_byte(gbc) << 8;
+                rgba |= bytestream2_get_byte(gbc) << 0;
+                rgba |= bytestream2_get_byte(gbc) << 24;
+                p[i] = rgba;
             }
 
             frame->palette_has_changed = 1;