libucl: new package

Libucl is a high performance and flexible JSON/YAML/etc. parser for C.

https://github.com/vstakhov/libucl



[Thomas:
  - remove hash file, should not be used for github downloads
  - rewrap Config.in help text
  - remove trailing white space in Config.in.
  - add missing host-pkgconf dependency, without which the package
    doesn't autoreconf properly.
  - fix license: it is BSD-2c, not just BSD.]

Signed-off-by: Nimai Mahajan <nimaim@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>