[jdk21u-dev] RFR: 8336342: Fix known X11 library locations in sysroot

[Aleksey Shipilev]

Allows cleaner cross-builds without supplying `--x-libraries` for custom-generated sysroots, e.g. crosstool-ng ones. I have been running with this patch for 3+ weeks in 21u-dev builds, and there were no problems.

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Commit messages:
 - Backport ee365d75cca6f33e5781fe514e557caba2b67c32

Changes: https://git.openjdk.org/jdk21u-dev/pull/896/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=896&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8336342
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/896.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/896/head:pull/896

PR: https://git.openjdk.org/jdk21u-dev/pull/896