RFR: 8267042: bug in monitor locking/unlocking on ARM32 C1 due to uninitialized BasicObjectLock::_displaced_header

[Boris Ulasevich]

Hi,

Could we have a review of this change?

The bug was discovered in ARM32 C1 monitor locking/unlocking: the 
displaced header is not initialized to the non-zero value which results in deadlock.

Thanks,
Boris

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

Commit messages:
 - test cleanup
 - adding reproducer to c1 jtreg tests
 - Fixing locking on ARM32 C1: initialize the displaced_header in C1_MacroAssembler::lock_object and native wrapper locking code

Changes: https://git.openjdk.java.net/jdk/pull/4218/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4218&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8267042
  Stats: 176 lines in 3 files changed: 172 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4218.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4218/head:pull/4218

PR: https://git.openjdk.java.net/jdk/pull/4218