lavfi: remove gradfun mp wrapper

The gradfun filter was already integrated natively in libavfilter.
Both filters issue the same output, and have a comparable performance.

See thread:
Subject: [FFmpeg-devel] [PATCH] lavfi: remove gradfun mp wrapper
Date: Fri,  5 Aug 2011 00:19:04 +0200

doc/filters.texi

@@ -935,7 +935,6 @@ The list of the currently supported filters follows:
 @item framestep
 @item fspp
 @item geq
-@item gradfun
 @item harddup
 @item hqdn3d
 @item hue

libavfilter/Makefile

@@ -97,7 +97,6 @@ OBJS-$(CONFIG_MP_FILTER) += libmpcodecs/vf_fixpts.o
 OBJS-$(CONFIG_MP_FILTER) += libmpcodecs/vf_framestep.o
 OBJS-$(CONFIG_MP_FILTER) += libmpcodecs/vf_fspp.o
 OBJS-$(CONFIG_MP_FILTER) += libmpcodecs/vf_geq.o
-OBJS-$(CONFIG_MP_FILTER) += libmpcodecs/vf_gradfun.o
 OBJS-$(CONFIG_MP_FILTER) += libmpcodecs/vf_harddup.o
 OBJS-$(CONFIG_MP_FILTER) += libmpcodecs/vf_hqdn3d.o
 OBJS-$(CONFIG_MP_FILTER) += libmpcodecs/vf_hue.o

libavfilter/avfilter.h

@@ -30,7 +30,7 @@
 
 #define LIBAVFILTER_VERSION_MAJOR  2
 #define LIBAVFILTER_VERSION_MINOR 28
-#define LIBAVFILTER_VERSION_MICRO  0
+#define LIBAVFILTER_VERSION_MICRO  1
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
                                                LIBAVFILTER_VERSION_MINOR, \

libavfilter/vf_mp.c

@@ -142,7 +142,6 @@ extern const vf_info_t vf_info_yvu9;
 extern const vf_info_t vf_info_lavcdeint;
 extern const vf_info_t vf_info_eq;
 extern const vf_info_t vf_info_eq2;
-extern const vf_info_t vf_info_gradfun;
 extern const vf_info_t vf_info_halfpack;
 extern const vf_info_t vf_info_dint;
 extern const vf_info_t vf_info_1bpp;
@@ -214,7 +213,6 @@ static const vf_info_t* const filters[]={
     &vf_info_framestep,
     &vf_info_fspp,
     &vf_info_geq,
-    &vf_info_gradfun,
     &vf_info_harddup,
     &vf_info_hqdn3d,
     &vf_info_hue,