Changes

Dockerfile: update CRIU to v3.12
New features
- build CRIU with Android NDK
- C/R of
 - IP RAW sockets
 - lsm: dump and restore any SELinux process label
 - support restoring ghost files on readonly mounts
Bugfixes
 - Do not lock network if running in the host network namespace
- Fix RPC configuration file handling
- util: don't leak file descriptors to third-party tools
- small fixes here and there
Improvements
- travis: switch to the Ubuntu Xenial
- travis-ci: Enable ia32 tests
- Many improvements and bug fixes in the libcriu
 - Changes in the API and ABI (SONAME increased from 1 to 2)
full diff:
https://github.com/checkpoint-restore/criu/compare/v3.11...v3.12
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

vendor: update buildkit to v0.6.1
Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>