release: Clear Containers 3.0.21
release: Clear Containers 3.0.21

- vendor: Re-vendor virtcontainers
- vendor: Vendor virtcontainers

167cbbd vendor: Re-vendor virtcontainers
00fe837 vendor: Vendor virtcontainers

Signed-off-by: Jose Carlos Venegas Munoz <821ab150128e889cb3ad9aab6e72689fd9ad26f2@intel.com>

clearcontainers/proxy,clearcontainers/proxy