main: cast Chmod argument to os.FileMode
main: cast Chmod argument to os.FileMode

This fixes a big red warning in my vim.

Signed-off-by: Kir Kolyshkin <3a017b8ddb3f9cf3e4a59978b004111bdeb97f08@gmail.com>

dqminh/runc,kolyshkin/runc,kolyshkin/runc,opencontainers/runc,opencontainers/runc,dqminh/runc,opencontainers/runc,rhatdan/runc,dqminh/runc,kolyshkin/runc,rhatdan/runc,rhatdan/runc,opencontainers/runc,rhatdan/runc,dqminh/runc,kolyshkin/runc