<AWT Dev> RFR: 8242559: Clean the "libawt_xawt" library from code for headless mode [v2]

[Sergey Bylokhov]

> 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

Sergey Bylokhov 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 'master' into JDK-8242559
 - 8242559: Clean the "libawt_xawt" library from code for headless mode

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/101/files
  - new: https://git.openjdk.java.net/jdk/pull/101/files/10c83cdc..2d707f2e

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=101&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=101&range=00-01

  Stats: 449258 lines in 4393 files changed: 368482 ins; 59508 del; 21268 mod
  Patch: https://git.openjdk.java.net/jdk/pull/101.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/101/head:pull/101

PR: https://git.openjdk.java.net/jdk/pull/101