RFR: 8253375: OSX build fails with Xcode 12.0 (12A7209) [v2]

[Paul Hohensee]

> Please review this small patch to enable the OSX build using Xcode 12.0.
> 
> Thanks,
> Paul

Paul Hohensee has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev
excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since
the last revision:

 - 8253375: Reverted CSystemColors.m patch, replaced sharedRuntime.cpp patch
 - Merge branch 'master' into JDK-8253375
 - JDK-8253375

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/348/files
  - new: https://git.openjdk.java.net/jdk/pull/348/files/5db5edc2..cb08da07

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=348&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=348&range=00-01

  Stats: 27610 lines in 391 files changed: 4691 ins; 21610 del; 1309 mod
  Patch: https://git.openjdk.java.net/jdk/pull/348.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/348/head:pull/348

PR: https://git.openjdk.java.net/jdk/pull/348