[crac] RFR: Add Checkpoint timeout

[KIRIYAMA Takuya]

Java process sometimes hangs when checkpoint for some reasons.
For example, this problems occurs if you specify certain options for CRAC_CRIU_OPTS.


# export CRAC_CRIU_OPTS=-V
# java -XX:CRaCCheckpointTo=/work/cp CRACTest
CR: Checkpoint ...

CRACTest process is not killed and is waiting for checkpoint.


# ls /work/cp
cppath  perfdata


To avoid this problem, I want to add the checkpoint timeout.
Can I submit a pull request to this repository? I would like you to review this change.

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Commit messages:
 - Add checkpoint timepout
 - Add checkpoint timepout
 - Add checkpoint timepout

Changes: https://git.openjdk.org/crac/pull/147/files
 Webrev: https://webrevs.openjdk.org/?repo=crac&pr=147&range=00
  Stats: 89 lines in 3 files changed: 88 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/crac/pull/147.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/147/head:pull/147

PR: https://git.openjdk.org/crac/pull/147