libxdmcp can optionally use arc4random_buf() from libbsd instead of it's own
random key generation code. As this is an optional dependency add a
PACKAGECONFIG for it and default to not using libbsd.
(From OE-Core rev: fe7780a9bbbfa4dcbbe457618a0842e91a3c6a0e)
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>