Vendor golang.org/x/sys to get the UtimesNanoAt function defined for all
unix-like OSes. The function will be used in a successive commit.
This also re-vendors the other dependencies from glide.yaml.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
This would help us build go-mtree on RHEL/CentOS and
distros where golang.org/x/crypto isn't provided or supported.
Signed-off-by: Lokesh Mandvekar <lsm5@fedoraproject.org>