8242559: Clean the "libawt_xawt" library from code for headless mode

[mrserb]

This bug extracted from JDK-8240290[1]

The libawt_xawt.so library is used by the headful toolkit, but it still
has some code related to the headless mode, which could be deleted.

In the fix, the HEADLESS related code was removed, to prove that we did
not build this library in HEADLESS mode, I added "#error This " to all
library files(but some of them already has it)

[1] https://bugs.openjdk.java.net/browse/JDK-8240290

The old review request:
https://mail.openjdk.java.net/pipermail/awt-dev/2020-April/015881.html

---

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change must be properly reviewed

Testing

	Linux x32	Linux x64	Windows x64	macOS x64
Build	✔️ (1/1 passed)	✔️ (5/5 passed)	✔️ (2/2 passed)	✔️ (2/2 passed)
Test (tier1)		✔️ (9/9 passed)	❌ (1/9 failed)	✔️ (9/9 passed)

Failed test task

• Windows x64 (hs/tier1 compiler)

Issue

• JDK-8242559: Clean the "libawt_xawt" library from code for headless mode

Reviewers

• Alexander Zuev (@azuev-java - Reviewer) ⚠️ Review applies to 10c83cd

Download

$ git fetch https://git.openjdk.java.net/jdk pull/101/head:pull/101
$ git checkout pull/101

[bridgekeeper]

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[openjdk]

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[mlbridge]

Webrevs

• 01: Full - Incremental (2d707f2)
• 00: Full (10c83cd)

[prrace]

Clearly these are there to prevent mistakes. So they add value at a tiny build time cost.
I don't see the point of removing them.

[mrserb]

Clearly these are there to prevent mistakes. So they add value at a tiny build time cost.
I don't see the point of removing them.

That's the point of the fix, instead of implementing two versions of each method in these files just prevent compilation of the file in the headless mode. As far as understand both solutions are equivalent, but an assertion at the start of the file a much cleaner.

[magicus]

I agree with Sergey. This is much cleaner. All steps towards cleaning up the spaghetti code regarding headless/not headless are important, even if they are small. It's like solving the thousand paper cuts issue; you have to address every individual cut, not matter how miniscule.

[openjdk]

@mrserb This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8242559: Clean the "libawt_xawt" library from code for headless mode

Reviewed-by: kizune

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 5 new commits pushed to the master branch:

• 7d3d4da: 8240709: Enable javax/swing/UI/UnninstallUIMemoryLeaks/UnninstallUIMemoryLeaks.java on all L&F
• 5d26229: 8255174: Vector API unit tests for missed public api code coverage
• b9186be: 6606767: resexhausted00[34] fail assert(!thread->owns_locks(), "must release all locks when leaving VM")
• 1191a63: 8199697: FIPS 186-4 RSA Key Generation
• 60d3fa2: 8255022: Documentation missing for Vector API zero methods

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[mrserb]

/integrate

[openjdk]

@mrserb Since your change was applied there have been 17 commits pushed to the master branch:

• ff5f226: 8255086: Update the root locale display names
• 8afdcae: 8255031: Update java/util/prefs/AddNodeChangeListener.java to report more failure info
• 0aa3c92: 8255262: Remove use of legacy custom @SPEC tag
• a0b687b: 8254854: [cgroups v1] Metric limits not properly detected on some join controller combinations
• f279ddf: 8248411: [aarch64] Insufficient error handling when CodeBuffer is exhausted
• 4634dbe: 8223312: Utilize handshakes instead of is_thread_fully_suspended
• cc50c8d: 8255196: Remove unused G1FullGCCompactionPoint::merge()
• ae72b52: 8255047: Add HotSpot UseDebuggerErgo flags
• 211bb62: 8255124: KeepAliveStreamCleaner may crash with java.lang.IllegalMonitorStateException: current thread is not owner
• 299e115: 8198395: Test javax/swing/plaf/metal/MetalLookAndFeel/Test8039750.java fails in mach5
• ... and 7 more: https://git.openjdk.java.net/jdk/compare/9ade94b727b54bfff248ef9fdd29d6386aba190c...master

Your commit was automatically rebased without conflicts.

Pushed as commit d8d9197.

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