vf_libopencv: add support for opencv 3

It dropped the old headers, but the replacements are already available
with opencv 2.
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>

configure

@@ -1774,6 +1774,7 @@ HEADERS_LIST="
     machine_ioctl_bt848_h
     machine_ioctl_meteor_h
     malloc_h
+    opencv2_core_core_c_h
     openjpeg_2_1_openjpeg_h
     openjpeg_2_0_openjpeg_h
     openjpeg_1_5_openjpeg_h
@@ -5481,7 +5482,9 @@ enabled libmp3lame        && require "libmp3lame >= 3.98.3" lame/lame.h lame_set
 enabled libnut            && require libnut libnut.h nut_demuxer_init -lnut
 enabled libopencore_amrnb && require libopencore_amrnb opencore-amrnb/interf_dec.h Decoder_Interface_init -lopencore-amrnb
 enabled libopencore_amrwb && require libopencore_amrwb opencore-amrwb/dec_if.h D_IF_init -lopencore-amrwb
-enabled libopencv         && require_pkg_config opencv opencv/cxcore.h cvCreateImageHeader
+enabled libopencv         && { check_header opencv2/core/core_c.h &&
+                               require_pkg_config opencv opencv2/core/core_c.h cvCreateImageHeader ||
+                               require_pkg_config opencv opencv/cxcore.h cvCreateImageHeader; }
 enabled libopenh264       && require_pkg_config openh264 wels/codec_api.h WelsGetCodecVersion
 enabled libopenjpeg       && { check_lib openjpeg-2.1/openjpeg.h opj_version -lopenjp2 -DOPJ_STATIC ||
                                check_lib openjpeg-2.0/openjpeg.h opj_version -lopenjp2 -DOPJ_STATIC ||

libavfilter/vf_libopencv.c

@@ -23,8 +23,14 @@
  * libopencv wrapper functions
  */
 
+#include "config.h"
+#if HAVE_OPENCV2_CORE_CORE_C_H
+#include <opencv2/core/core_c.h>
+#include <opencv2/imgproc/imgproc_c.h>
+#else
 #include <opencv/cv.h>
 #include <opencv/cxcore.h>
+#endif
 #include "libavutil/avstring.h"
 #include "libavutil/common.h"
 #include "libavutil/file.h"