missing: add __NR_getrandom for a few more archs

Mips has getrandom() too, but there's just too many variants
for me too care. Either someone who cares does it, or they get
compile-time warnings with old kernel headers.
missing: add IFLA_BRPORT_LEARNING and friends

IFLA_BRPORT_LEARNING was added in v3.10-rc4-583-g9ba18891f7,
and IFLA_BRPORT_UNICAST_FLOOD in v3.10-rc4-584-g867a59436f.
Do not check for existence of remote binaries

systemd-run would fail when run with -M or -H and an absolute path,
if this path did not exists locally. Allow it to continue, since we
don't have a nice way of checking if the binary exists remotely.

The case where -M or -H is used and a local path is unchanged, and we
still iterate over $PATH to find the binary. We need to convert to an
absolute path, and we don't have a nice mechanism to check remotely,
so we assume that the binary will be located in the same place locally
and remotely.

http://lists.freedesktop.org/archives/systemd-devel/2014-November/025418.html