RFR: 8313374: --enable-ccache's CCACHE_BASEDIR breaks builds [v6]

[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 true/false for REWRITE_PATHS_RELATIVE and initialize it
   - suggested by Erik Joelsson

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15080/files
  - new: https://git.openjdk.org/jdk/pull/15080/files/72707a57..c1082c41

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15080&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15080&range=04-05

  Stats: 4 lines in 1 file changed: 1 ins; 0 del; 3 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