vf_fspp: make compile without Libav internals

Make vf_fspp compile without using internal Libav/FFmpeg files and
compile it by default.

Makefile

@@ -61,8 +61,7 @@ SRCS_COMMON-$(FAAD)                  += libmpcodecs/ad_faad.c
 SRCS_COMMON-$(FASTMEMCPY)            += libvo/aclib.c
 
 # These filters use private headers and do not work with shared libavcodec.
-SRCS_COMMON-$(FFMPEG_INTERNALS)      += libmpcodecs/vf_fspp.c \
-                                        libmpcodecs/vf_mcdeint.c \
+SRCS_COMMON-$(FFMPEG_INTERNALS)      += libmpcodecs/vf_mcdeint.c \
                                         libmpcodecs/vf_spp.c \
 
 SRCS_COMMON-$(FREETYPE)              += sub/font_load_ft.c
@@ -312,6 +311,7 @@ SRCS_COMMON = asxparser.c \
               libmpcodecs/vf_flip.c \
               libmpcodecs/vf_format.c \
               libmpcodecs/vf_framestep.c \
+              libmpcodecs/vf_fspp.c \
               libmpcodecs/vf_geq.c \
               libmpcodecs/vf_gradfun.c \
               libmpcodecs/vf_halfpack.c \

libmpcodecs/vf.c

@@ -138,6 +138,7 @@ static const vf_info_t *const filter_list[] = {
     &vf_info_lavc,
     &vf_info_lavcdeint,
     &vf_info_screenshot,
+    &vf_info_fspp,
     &vf_info_uspp,
 
     &vf_info_dvbscale,
@@ -182,7 +183,6 @@ static const vf_info_t *const filter_list[] = {
     &vf_info_hue,
 #ifdef CONFIG_FFMPEG_INTERNALS
     &vf_info_spp,
-    &vf_info_fspp,
     &vf_info_mcdeint,
 #endif
     &vf_info_geq,

libmpcodecs/vf_fspp.c

@@ -38,6 +38,10 @@
 #include <inttypes.h>
 #include <math.h>
 
+#include <libavutil/intreadwrite.h>
+#include <libavutil/mem.h>
+#include <libavcodec/avcodec.h>
+
 #include "config.h"
 
 #include "mp_msg.h"
@@ -46,15 +50,9 @@
 #include "mp_image.h"
 #include "vf.h"
 #include "libvo/fastmemcpy.h"
+#include "mangle.h"
 
-#include "libavutil/internal.h"
-#include "libavutil/intreadwrite.h"
-#include "libavutil/mem.h"
-#include "libavcodec/avcodec.h"
-#include "libavcodec/dsputil.h"
-
-#undef free
-#undef malloc
+typedef short DCTELEM;
 
 //===========================================================================//
 #define BLOCKSZ 12