package/libtorrent-rasterbar: bump to version 1.2.0

package/libtorrent-rasterbar: bump to version 1.2.0

- Drop boost-chrono, replaced by std::chrono since
  https://github.com/arvidn/libtorrent/commit/78bc2698327069aa69ff7460b9314cbe45bd4d66
- Drop boost random, replace by standard number classes since
  https://github.com/arvidn/libtorrent/commit/fef94a4c5254e2280b601ab3ea211cc0193fecaa
- Add two patches to fix build on uclibc
- Needs exception_ptr since
  https://github.com/arvidn/libtorrent/commit/5c361715da9d20d63b019d7fc4ce772cdecd7138

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>