update gen.sh

support clang 3.4
change crate names

avutil --> avutil52
avcodec --> avcodec54
avdevice --> avdevice54
avfilter --> avfilter3
avformat --> avformat54
swresample --> swresample54
swscale --> swscale2
update avutil52

bindings generated from 52.66.100 (FFmpeg 2.2.1)
update swscale2

binidings are generated from swscale 2.5.102 (FFmpeg 2.2.1)
update swresample0

bindings are generated from swresample 0.18.100 (FFmpeg 2.2.1)
update avfilter3

bindings are generated from avfilter 3.90.100
add avcodec55, avdevice55 avfilter4 avformat55

update rust-ffmpeg
suppress non_camel_case_types warnings