[crac] RFR: 8348927: [CRaC] Handle boot-id not ending with newline

[Timofei Pushkin]

Besides fixing the problem described in the JDK issue:
- Report errors through `log_error(crac)`, not `perror()`
- Don't leak a file descriptor on error

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Commit messages:
 - Handle boot-id not ending with newline

Changes: https://git.openjdk.org/crac/pull/196/files
  Webrev: https://webrevs.openjdk.org/?repo=crac&pr=196&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8348927
  Stats: 39 lines in 1 file changed: 27 ins; 1 del; 11 mod
  Patch: https://git.openjdk.org/crac/pull/196.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/196/head:pull/196

PR: https://git.openjdk.org/crac/pull/196