RFR: 8320655: awt screencast robot spin and sync issues with native libpipewire api [v2]

[Anton Bobrov]

> This patch addresses the issues described in the https://bugs.openjdk.org/browse/JDK-8320655 by fixing the proper locking and signalling around libpipewire thread loop condition variables and also fixing libpipewire error detection and signalling and propagation to the screencast API. This makes the screencast robot stable enough to consistently make it thru the entire javax/swing jtreg suite without hanging and also significantly reduces CPU consumption as there is no longer any burning spinners since they are now waiting on related conditions proper.

Anton Bobrov 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 two additional commits since the last revision:

 - Merge branch 'openjdk:master' into screencast_robot
 - 8320655: awt screencast robot spin and sync issues with native libpipewire api

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Changes:
  - all: https://git.openjdk.org/jdk/pull/16794/files
  - new: https://git.openjdk.org/jdk/pull/16794/files/6805f72d..e6023b32

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16794&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16794&range=00-01

  Stats: 38277 lines in 1287 files changed: 26232 ins; 6214 del; 5831 mod
  Patch: https://git.openjdk.org/jdk/pull/16794.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16794/head:pull/16794

PR: https://git.openjdk.org/jdk/pull/16794