seafile: import seafile-server package and its dependencies

Signed-off-by: Gergely Kiss <mail.gery@gmail.com>
Tested-by: Gergely Kiss <mail.gery@gmail.com>
libsearpc: use commit hash in version instead of release tag

Signed-off-by: Gergely Kiss <mail.gery@gmail.com>
Tested-by: Gergely Kiss <mail.gery@gmail.com>
seafile: fetch sources using commit hashes instead of release tags

Avoids source filename conflicts and the need to delete source packages
at the end of the prepare stage. This has forced the buildenv to rebuild
the packages even if they were built already.

Signed-off-by: Gergely Kiss <mail.gery@gmail.com>