RFR: 8354920: SA core file support on Linux only prints error messages when debug logging is enabled

[Daniel Jeliński]

Currently if loading a core file fails, the diagnostic information provided on different systems is different; on MacOS we produce an error message, while on Linux we only print information if debug logging is enabled.

This PR adds some new messages on Linux to match MacOSX, and changes some of the diagnostic output to error level instead of debug. Additionally, if opening the core or the exe file fails, the system error message (strerror) is printed.

Tier1-3 testing clean.

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Commit messages:
 - Update copyright
 - Report more information on error

Changes: https://git.openjdk.org/jdk/pull/24722/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24722&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8354920
  Stats: 21 lines in 2 files changed: 8 ins; 0 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/24722.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24722/head:pull/24722

PR: https://git.openjdk.org/jdk/pull/24722