Update Changelog for the 0.8.6 Release

Changelog

@@ -1,6 +1,37 @@
 Entries are sorted chronologically from oldest to youngest within each release,
 releases are sorted from youngest to oldest.
 
+
+version 0.8.6:
+
+- Build system fixes: Fix Altivec detection (Debian Bug#701710) and fix
+  CAF demuxer dependencies
+- Various minor documentation fixes
+- dsputil: fix invalid array indexing
+- h264: check for luma and chroma bit depth being equal (CVE-2013-2277)
+- indeo3: initialise pixel planes on allocation
+- lavf: fix arithmetic overflows in avformat_seek_file()
+- matroskadec: request a read buffer for the wav header
+- mp3: exit on parsing error in mp_decode_frame
+- oggdec: make sure the private parse data is cleaned up
+- parser: fix large overreads
+- pthread: set the frame properties from the thread context, not user
+- various potentially security relevant fixes to the shorten decoder
+- update year to 2013
+- vmdaudio: fix invalid reads when packet size is not a multiple of chunk size
+- vorbisdec: Error on bark_map_size equal to 0 (CVE-2013-0894)
+- wmadec: require block_align to be set
+- wmaprodec: return an error, not 0, when the input is too small
+- xxan: fix invalid memory access in xan_decode_frame_type0()
+- lzo: fix overflow checking in copy_backptr()
+- flacdec: simplify bounds checking in flac_probe() to avoid undefined behavior.
+- atrac3: avoid oversized shifting in decode_bytes().
+- png: use av_mallocz_array() for the zlib zalloc function, avoids accessing uninitialized memory.
+- wmaprodec: require block_align to be set, avoids infinite loop.
+- ivi_common: do not call MC for intra frames when dc_transform is unset
+- roqvideodec: fix a potential infinite loop in roqvideo_decode_frame().
+
+
 version 0.8.5:
 
 - Several bugs and crashes have been fixed in the following codecs: