Declare required development packages

[fenollp]

I have trouble linking on Debian 8 and OSX 10.11.
Could you guys write a quick list of dep+vsn in /README.md?

On debian I have this:

error: linking with `cc` failed: exit code: 1
note: "cc" "-Wl,--as-needed" "-m64" "-L" "/home/pete/.multirust/toolchains/nightly/lib/rustlib/x86_64-unknown-linux-gnu/lib" "/home/pete/wefwefwef/chaptrs.git/target/debug/chaptrs.0.o" "-o" "/home/pete/wefwefwef/chaptrs.git/target/debug/chaptrs" "-Wl,--gc-sections" "-pie" "-nodefaultlibs" "-L" "/home/pete/wefwefwef/chaptrs.git/target/debug" "-L" "/home/pete/wefwefwef/chaptrs.git/target/debug/deps" "-L" "/home/pete/.multirust/toolchains/nightly/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-L" "/home/pete/wefwefwef/chaptrs.git/.rust/lib/x86_64-unknown-linux-gnu" "-L" "/home/pete/wefwefwef/chaptrs.git/lib/x86_64-unknown-linux-gnu" "-Wl,-Bstatic" "-Wl,-Bdynamic" "/home/pete/wefwefwef/chaptrs.git/target/debug/deps/libffmpeg-805255d617bd8363.rlib" "/home/pete/wefwefwef/chaptrs.git/target/debug/deps/libffmpeg_sys-fadf153a42f32bb4.rlib" "/home/pete/wefwefwef/chaptrs.git/target/debug/deps/liblibc-540159808ccfa9ab.rlib" "/home/pete/wefwefwef/chaptrs.git/target/debug/deps/libbitflags-eec34728826d9769.rlib" "/home/pete/.multirust/toolchains/nightly/lib/rustlib/x86_64-unknown-linux-gnu/lib/libstd-8cf6ce90.rlib" "/home/pete/.multirust/toolchains/nightly/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcollections-8cf6ce90.rlib" "/home/pete/.multirust/toolchains/nightly/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc_unicode-8cf6ce90.rlib" "/home/pete/.multirust/toolchains/nightly/lib/rustlib/x86_64-unknown-linux-gnu/lib/librand-8cf6ce90.rlib" "/home/pete/.multirust/toolchains/nightly/lib/rustlib/x86_64-unknown-linux-gnu/lib/liballoc-8cf6ce90.rlib" "/home/pete/.multirust/toolchains/nightly/lib/rustlib/x86_64-unknown-linux-gnu/lib/liballoc_jemalloc-8cf6ce90.rlib" "/home/pete/.multirust/toolchains/nightly/lib/rustlib/x86_64-unknown-linux-gnu/lib/liblibc-8cf6ce90.rlib" "/home/pete/.multirust/toolchains/nightly/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcore-8cf6ce90.rlib" "-l" "avutil" "-l" "avcodec" "-l" "avdevice" "-l" "avformat" "-l" "avfilter" "-l" "avresample" "-l" "swresample" "-l" "swscale" "-l" "dl" "-l" "pthread" "-l" "gcc_s" "-l" "rt" "-l" "pthread" "-l" "c" "-l" "m" "-Wl,-rpath,$ORIGIN/../../../../.multirust/toolchains/nightly/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-Wl,-rpath,/usr/local/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-l" "compiler-rt"
note: /usr/bin/ld: cannot find -lswresample
collect2: error: ld returned 1 exit status

Mainly: does it depend on ffmpeg (from the Ffmpeg project), avconv (because both my platforms ask for libavutil)?
Or: do you know an easy way to install libavutil on debian or osx?
I think I'll test my code using only Travis CI for now :D

[meh]

We're trying to figure that out, see ongoing discussion here.

[klesun]

sudo apt-get install libavutil-dev
sudo apt-get install libavformat-dev
sudo apt-get install libavfilter-dev
sudo apt-get install libavdevice-dev
sudo apt-get install libclang-dev

See meh/rust-ffmpeg-sys#10