Merge commit 'a786c8259dafeca9744252230b5d78f67810770c'

* commit 'a786c8259dafeca9744252230b5d78f67810770c':
  idct: Split off Xvid IDCT

Conflicts:
	libavcodec/Makefile
	libavcodec/mpeg4videodec.c
	libavcodec/x86/Makefile
	libavcodec/x86/idctdsp_init.c

This split is somewhat restructured leaving the xvid IDCT available
outside mpeg4 if manually selected.

The code also could not be merged unchanged as it conflicted with a
bugfix in FFmpeg

Merged-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/idctdsp.c

@@ -24,6 +24,7 @@
 #include "faanidct.h"
 #include "idctdsp.h"
 #include "simple_idct.h"
+#include "xvididct.h"
 
 av_cold void ff_init_scantable(uint8_t *permutation, ScanTable *st,
                                const uint8_t *src_scantable)
@@ -299,6 +300,9 @@ av_cold void ff_idctdsp_init(IDCTDSPContext *c, AVCodecContext *avctx)
     c->put_signed_pixels_clamped = put_signed_pixels_clamped_c;
     c->add_pixels_clamped        = add_pixels_clamped_c;
 
+    if (CONFIG_MPEG4_DECODER && avctx->idct_algo == FF_IDCT_XVIDMMX)
+        ff_xvididct_init(c, avctx);
+
     if (ARCH_ALPHA)
         ff_idctdsp_init_alpha(c, avctx, high_bit_depth);
     if (ARCH_ARM)