RFR: 8306767: Concurrent repacking of extra data in MethodData is potentially unsafe [v9]

[Emanuel Peter]

> I'm making sure that `allocate_bci_to_data` is only called when holding the `extra_data_lock`, so that no concurrent calls of it can ever occur.
> 
> Testing: tier1-3 and stress.

Emanuel Peter has updated the pull request incrementally with one additional commit since the last revision:

  remove more locking

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/16840/files
  - new: https://git.openjdk.org/jdk/pull/16840/files/70327d38..30e5aebc

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16840&range=08
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16840&range=07-08

  Stats: 15 lines in 1 file changed: 1 ins; 7 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/16840.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16840/head:pull/16840

PR: https://git.openjdk.org/jdk/pull/16840