[foreign-memaccess+abi] RFR: 8277845: Clean up use if ProgrammableInvoker/UpcallHandler.USE_INTRINSICS in tests. [v4]

[Jorn Vernee]

> This PR cleans up use of USE_INTRINSICS flags in the tests, which was removed a while ago.
> 
> I also noticed that TestMatrix.java didn't have a copyright header, so I've added one. (the diff looks a little mangled as a result). It also wasn't setting the UPCALL_TEST_TYPE flag when running TestUpcall, so I've added that flag.

Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:

  - Move LoadLibrary calls to base classes.
  - Make static field only used in the base class private.
  - Capitalize static field names.

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

Changes:
  - all: https://git.openjdk.java.net/panama-foreign/pull/629/files
  - new: https://git.openjdk.java.net/panama-foreign/pull/629/files/329cf54e..c7aa2cb6

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=629&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=629&range=02-03

  Stats: 32 lines in 4 files changed: 13 ins; 6 del; 13 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/629.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/629/head:pull/629

PR: https://git.openjdk.java.net/panama-foreign/pull/629