[jdk21u-dev] RFR: 8327460: Compile tests with the same visibility rules as product code

[Goetz Lindenmaier]

I would like to backport this to keep the test suite close to head.
This simplifies later backports.

I had to resolve some files.

test/jdk/java/foreign/critical/libCritical.c
This was added by "8254693: Add Panama feature to pass heap segments to native code". Omitted.

patching file test/jdk/java/foreign/libLibraryLookup.c
patching file test/jdk/java/foreign/libLookupTest.c
test/jdk/java/foreign/libSafeAccess.c
Resolved because "8310643: Misformatted copyright messages in FFM" is not in 21

patching file test/jdk/java/foreign/nested/libNested.c
patching file test/jdk/java/foreign/shared.h
Resolved because "8318175: AIX PPC64: Handle alignment of double in structs" is not in 21 

patching file test/jdk/java/foreign/stackwalk/libAsyncStackWalk.cpp
Resolved because "8324799: Use correct extension for C++ test headers" is not in 21.

patching file test/jdk/java/foreign/stackwalk/libReentrantUpcalls.c
patching file test/jdk/java/foreign/stackwalk/libStackWalk.c
Resolved because "8310643: Misformatted copyright messages in FFM" is not in 21

test/lib/jdk/test/lib/thread/libVThreadPinner.c
This was added by "8320707: Virtual thread test updates", which was backported to 21.
But this file was dropped from the backport as it is not applicable to 21.

test/micro/org/openjdk/bench/java/lang/foreign/libCriticalCalls.c
This was added by "8254693: Add Panama feature to pass heap segments to native code". Omitted.

Executed affected tests and micro benchmarks.

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Commit messages:
 - Backport cc9a8aba67f4e240c8de2d1ae15d1b80bfa446a0

Changes: https://git.openjdk.org/jdk21u-dev/pull/1301/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1301&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8327460
  Stats: 293 lines in 37 files changed: 69 ins; 153 del; 71 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1301.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1301/head:pull/1301

PR: https://git.openjdk.org/jdk21u-dev/pull/1301