RFR: 8377326: [PPC64] build without C1 and C2 broken [v2]

[Martin Doerr]

> Trivial fixes to get the build working when `--with-jvm-features=-compiler1,-compiler2` is configured.
> `c_calling_convention` is used by the native wrapper. Some unused integer variables need to be defined. `frame_size_in_words` is unused.

Martin Doerr has updated the pull request incrementally with one additional commit since the last revision:

  Update Copyright header.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/29595/files
  - new: https://git.openjdk.org/jdk/pull/29595/files/a2627ac4..0a408ef0

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=29595&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=29595&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/29595.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29595/head:pull/29595

PR: https://git.openjdk.org/jdk/pull/29595