RFR: 8313374: --enable-ccache's CCACHE_BASEDIR breaks builds [v3]

[Jan Kratochvil]

> https://bugs.openjdk.org/browse/JDK-8313374
> --enable-ccache's CCACHE_BASEDIR breaks builds

Jan Kratochvil has updated the pull request incrementally with one additional commit since the last revision:

  Use test for checking $ALLOW_ABSOLUTE_PATHS_IN_OUTPUT.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/15080/files
  - new: https://git.openjdk.org/jdk/pull/15080/files/eaa42e85..eb4a4ee7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15080&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15080&range=01-02

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/15080.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15080/head:pull/15080

PR: https://git.openjdk.org/jdk/pull/15080