RFR: 8210927: JDB tests do not update source after doing a redefine class

[Alex Menkov]

The fix executes "use" jdb command after class redifinition to improve test logs (print correct source line)

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Commit messages:
 - JdbTest.redefineClass updates source path

Changes: https://git.openjdk.java.net/jdk/pull/5664/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5664&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8210927
  Stats: 18 lines in 3 files changed: 8 ins; 0 del; 10 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5664.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5664/head:pull/5664

PR: https://git.openjdk.java.net/jdk/pull/5664