webp: do not call av_frame_free() on the user-provided frame

Fixes double-free on error.
webp: add a special case for a huffman table with only 1 symbol

The vlc reader cannot handle 0-bit huffman codes. For most
situations WebP uses the "simple" huffman coding for this case,
but that will only handle symbols up to 255. For the LZ77 distance
codes, larger symbol values are needed, so it can happen in rare
cases that a normal huffman table is used that only has a single
symbol.
dcadec: Decode LFE to avoid adding random data when downmixing with LFE

Signed-off-by: Tim Walker <tdskywalker@gmail.com>
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
libvpx: do not mark VP9 as experimental when using libvpx >= 1.3.0

Signed-off-by: Diego Biurrun <diego@biurrun.de>
dynamic loading of shared faac library
configure: temp hack to workaround new freetype2 headers
no Werror on implicit-function-declaration and missing-prototypes
custom icon and windows resource
use upstream version tag, my repo is always rebased