Add libtorrent-rasterbar 1.1 support

[andreygursky]

hrktorrent cannot be compiled on Debian testing (Buster) with libtorrent-rasterbar 1.1.4.

[andreygursky]

Debian 9 stable (Stretch) has libtorrent-rasterbar 1.1.1, so building hrktorrent is likely to fail there also.

[barracuda156]

@hrkfdn Any update on this? libtorrent-rasterbar is at 2.0.10 now: https://ports.macports.org/port/libtorrent-rasterbar