[crac] RFR: 8328344: [CRaC] Avoid error when running with -XX:+PerfDisableSharedMem [v5]

[Volker Simonis]

> CRaC tries to unconditionally restore the hsperf file, even if the checkpointed JVM process was started with `-XX:+PerfDisableSharedMem`.
> 
> The fix is trivial: check for the existence of the hsperf file in `PerfMemoryLinux::restore()` just as we already do it in `PerfMemoryLinux::checkpoint()`.

Volker Simonis has updated the pull request incrementally with one additional commit since the last revision:

  Extract delay to constant

-------------

Changes:
  - all: https://git.openjdk.org/crac/pull/153/files
  - new: https://git.openjdk.org/crac/pull/153/files/edee8cc0..19dd2d0c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=crac&pr=153&range=04
 - incr: https://webrevs.openjdk.org/?repo=crac&pr=153&range=03-04

  Stats: 4 lines in 1 file changed: 1 ins; 1 del; 2 mod
  Patch: https://git.openjdk.org/crac/pull/153.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/153/head:pull/153

PR: https://git.openjdk.org/crac/pull/153