RFR: 8261098: Add clhsdb "findsym" command

[Chris Plummer]

Add "findsym" to clhsdb. See the CR and CSR for details. The CSR still needs a reviewer.

There is one other somewhat unrelated fix in the test:

 -            String value = parts[1];
 +           String value = parts[1].split(linesep)[0];

This is suppose to capture just the value at the specified address, but it also captures the newline and some text after. The result if that when `findpc <value>` is executed, it also executes another command or two of garbage commands after that, which produce errors. They were not impacting the test, but were noticeable in the log. I first noticed it when similar code in the new part of the test had the same issue.

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Commit messages:
 - Add clhsdb findsym command.

Changes: https://git.openjdk.java.net/jdk/pull/2567/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2567&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8261098
  Stats: 69 lines in 3 files changed: 61 ins; 0 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2567.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2567/head:pull/2567

PR: https://git.openjdk.java.net/jdk/pull/2567