Contribs: use openjpeg in libav/ffmpeg

So that we have jp2k support on Windows and MacOS

NEWS

@@ -66,6 +66,7 @@ Codecs:
    The Schroedinger module should be prefered to the Dirac one
  * Support for WMV Images, aka WMVP and WVP2, as used by Photo Story
  * EIA-608 closed captions improvements
+ * Support for JPEG 2000 and Motion JPEG 2000 in the Windows and Mac binaries
 
 Demuxers:
  * New images demuxer supporting jpeg, png, targa, xcf, git, tiff, bmp, pcx, lbm

contrib/src/ffmpeg/rules.mak

@@ -11,6 +11,7 @@ FFMPEGCONF = \
 	--disable-decoder=libvpx \
 	--enable-libgsm \
 	--enable-libvpx \
+	--enable-libopenjpeg \
 	--disable-debug \
 	--enable-gpl \
 	--enable-postproc \
@@ -22,7 +23,7 @@ FFMPEGCONF = \
 	--disable-protocols \
 	--disable-avfilter \
 	--disable-network
-DEPS_ffmpeg = zlib gsm vpx $(DEPS_vpx)
+DEPS_ffmpeg = zlib gsm vpx $(DEPS_vpx) openjpeg
 
 # Optional dependencies
 ifdef BUILD_ENCODERS