[lilliput-jdk17u:lilliput] RFR: 8308647: [Lilliput/JDK17] Fix cross-builds

[Roman Kennke]

Some arches still require arrayOopDesc::header_size(BasicType) that we removed because it returns word-sized header-size, in favour of similar methods that return byte-sized header-size. Let's re-instate this old method to make cross-builds happy.

It also reduces the upstream diff. Let's see what the GHA of cross-builds say.

Testing:
 - [ ] GHA
 - [ ] build

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

Commit messages:
 - Add assert
 - 8308647: [Lilliput/JDK17] Fix cross-builds

Changes: https://git.openjdk.org/lilliput-jdk17u/pull/24/files
 Webrev: https://webrevs.openjdk.org/?repo=lilliput-jdk17u&pr=24&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8308647
  Stats: 12 lines in 1 file changed: 12 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/lilliput-jdk17u/pull/24.diff
  Fetch: git fetch https://git.openjdk.org/lilliput-jdk17u.git pull/24/head:pull/24

PR: https://git.openjdk.org/lilliput-jdk17u/pull/24