RFR: 8240908: RetransformClass does not know about MethodParameters attribute [v3]

[Alex Menkov]

> Changes:
> - ClassFileReconstituter is updated to restore "MethodParameters" attribute;
> - handling of the attribute in VM_RedefineClasses is moved to be consistent with other code (like local variable table);
> - copied ClassTransformer class (from test/jdk/com/sun/jdi/lib/jdb) to /test/lib as it's used by tests from hotspot and jdk (and also by test from Valhalla repo); Will file a follow up issues to updates tests and remove the class from test/jdk/com/sun/jdi/lib/jdb

Alex Menkov has updated the pull request incrementally with one additional commit since the last revision:

  Simplified the test, added comments

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7180/files
  - new: https://git.openjdk.java.net/jdk/pull/7180/files/bd89d7b7..c21d2455

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7180&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7180&range=01-02

  Stats: 209 lines in 1 file changed: 37 ins; 161 del; 11 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7180.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7180/head:pull/7180

PR: https://git.openjdk.java.net/jdk/pull/7180