RFR: 8293416: ZGC: Set mark bit with unconditional atomic ops

[hev]

**Summary**
Support to set ZGC mark bit with unconditional atomic ops.

**Motivation**
ZGC currently modify mark-bitmap by a conditional atomic operation (cmpxchg). This way is not optimal, which will retry the loop when cmpxchg fails.

**Description**
First, This patch-set add an new unconditional atomic operation: Atomic::fetch_and_or, which is implemented in different ways for different CPU architectures:

* Exclusive access: Non-nested loop


retry:
  ll old_val, addr
  or new_val, old_val, set_val
  sc new_val, addr
  beq retry


* Atomic access: One instruction


ldset old_val, set_val, addr


* Generic: Fallback to cmpxchg or use c++ __atomic_fetch_or

**Testing**
* jtreg tests
* benchmark tests

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Commit messages:
 - 8293416: ZGC: Set mark bit with unconditional atomic ops

Changes: https://git.openjdk.org/jdk/pull/10182/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10182&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8293416
  Stats: 467 lines in 18 files changed: 449 ins; 8 del; 10 mod
  Patch: https://git.openjdk.org/jdk/pull/10182.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10182/head:pull/10182

PR: https://git.openjdk.org/jdk/pull/10182