libcontainer/ignoreTerminateErrors: simplify for Go 1.16+
libcontainer/ignoreTerminateErrors: simplify for Go 1.16+

One less TODO in the code, yay!

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

kolyshkin/runc,opencontainers/runc,opencontainers/runc,kolyshkin/runc,opencontainers/runc,opencontainers/runc,kolyshkin/runc,kolyshkin/runc