RFR: 6383195: javax.crypto.spec.PBEKeySpec is not thread safe [v2]

[Bradford Wetmore]

> Simple fix to a long-standing threading bug to help clear the bug backlog.  
> 
> Without the synchronized, the test case fails almost immediately.  
> 
> Running JPRT with tier1/tier2.

Bradford Wetmore has updated the pull request incrementally with one additional commit since the last revision:

  Minor update to better note failures

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/9668/files
  - new: https://git.openjdk.org/jdk/pull/9668/files/13b296e4..c932188b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9668&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9668&range=00-01

  Stats: 15 lines in 1 file changed: 11 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/9668.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9668/head:pull/9668

PR: https://git.openjdk.org/jdk/pull/9668