DAEMON: share screen no longer works

Issue generated from Tuleap's migration script. Originally submitted by: Stepan Salenikovich (ssalenik)

Trying to share the screen failsin the daemon. Seems likely related to changes in ffmpeg (eg: compiling ffmpeg from contrib). Trying to share the screen produces the following log in the daemon:

[1477345175.001|19163|video\_input.cpp:479     ] MRL: 'display://:0+3287,408 444x284'
[1477345175.001|19284|media\_decoder.cpp:97    ] Trying to open device dummyFilename with format sdp, pixel format , size 0x0, rate 0.000000
[New Thread 0x7fffa2ffd700 (LWP 19285)]
[1477345175.001|19284|media\_decoder.cpp:112   ] Using format sdp
[1477345175.001|19284|media\_decoder.cpp:143   ] Finding stream info
[1477345175.002|19285|sinkclient.cpp:181      ] ShmHolder[Ring\_shm\_19163\_0]: new sizes: f=0, a=103
[1477345175.002|19285|sinkclient.cpp:147      ] ShmHolder: new holder 'Ring\_shm\_19163\_0'
[1477345175.002|19285|video\_input.cpp:164     ] VideoInput ready to capture
[1477345175.002|19284|media\_decoder.cpp:149   ] Finding stream info DONE
[1477345175.002|19285|media\_decoder.cpp:66    ] Cannot find format "x11grab"
[1477345175.002|19284|media\_decoder.cpp:196   ] Audio decoding using libopus with {2 channels, 48000Hz}
[1477345175.002|19285|media\_decoder.cpp:97    ] Trying to open device :0+3287,408 with format x11grab, pixel format , size 440x280, rate 25.000000
[1477345175.002|19285|media\_decoder.cpp:110   ] avformat\_open\_input failed: Protocol not found
[1477345175.002|19285|video\_input.cpp:341     ] Could not open input ":0+3287,408"
[1477345175.002|19285|video\_input.cpp:186     ] VideoInput closed