RFR: 8367045: [Linux] Dead keys not working [v5]

[Thiago Milczarek Sayao]

> The bug report is on Linux Mint which does not use ibus (the gnome default).
> 
> With this change, it continues to work on ibus, but also works works without it (on mint) and with fcitx.
> 
> It seems it's correct - but it's weird that it needed those bits before. I would say it's related to  `IBUS_ENABLE_SYNC_MODE` (see [this comment](https://github.com/openjdk/jfx/pull/1080#issuecomment-2412202297) on #1080.), but it seems to be still set to 0 on Ubuntu 24.04.
> 
> @Glavo: Can you check if Chinese input is still correct?
> @andzsinszan: Can you check for Japanese?

Thiago Milczarek Sayao has updated the pull request incrementally with two additional commits since the last revision:

 - Restore IBUS_ENABLE_SYNC_MODE
 - Restore IBUS_ENABLE_SYNC_MODE

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

Changes:
  - all: https://git.openjdk.org/jfx/pull/1922/files
  - new: https://git.openjdk.org/jfx/pull/1922/files/9e4157df..a9ea6ba7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1922&range=04
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1922&range=03-04

  Stats: 3 lines in 1 file changed: 3 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jfx/pull/1922.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1922/head:pull/1922

PR: https://git.openjdk.org/jfx/pull/1922