[foreign-memaccess+abi] RFR: 8311594: Avoid GlobalSession liveness check

[Jorn Vernee]

This patch overrides `checkValidStateRaw` in GlobalSession, to do nothing. The current `checkValidStateRaw` in MemorySessionImpl checks the owner thread, and liveness, which are both not needed for the global session.

Since the state field is mutable, I found that the JIT can not fold away the liveness check. This has a very marginal effect on performance, but since the fix is also very non-intrusive, I think it's okay to do.

I've added 2 new benchmarks that I've used to measure the difference. One measures the performance of MS::copy, and the other measures MS::get. Both use a special `ALL` segment which spans `0` to `Long.MAX_VALUE`, which means that the target address can be used as an offset when doing the accesses. This helps the bounds checks being eliminated, and makes the result of overriding `checkValidStateRaw` in GlobalSession easier to see.

Here are some of the interesting numbers:

Before:


Benchmark                                  Mode  Cnt  Score   Error  Units
MemorySegmentCopyALL.panama_ALL_to_ALL     avgt   30  7.788 ± 0.029  ns/op
MemorySegmentCopyALL.unsafe_array_to_addr  avgt   30  7.543 ± 0.018  ns/op

Benchmark                               Mode  Cnt  Score   Error  Units
MemorySegmentGet.segment_ALL_unaligned  avgt   30  0.486 ± 0.002  ns/op
MemorySegmentGet.unsafe                 avgt   30  0.398 ± 0.003  ns/op


After:


Benchmark                                  Mode  Cnt  Score   Error  Units
MemorySegmentCopyALL.panama_ALL_to_ALL     avgt   30  7.571 ± 0.017  ns/op
MemorySegmentCopyALL.unsafe_array_to_addr  avgt   30  7.550 ± 0.019  ns/op

Benchmark                               Mode  Cnt  Score   Error  Units
MemorySegmentGet.segment_ALL_unaligned  avgt   30  0.409 ± 0.002  ns/op
MemorySegmentGet.unsafe                 avgt   30  0.397 ± 0.003  ns/op

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

Commit messages:
 - rename benchmark methods
 - Drop Global Access Check

Changes: https://git.openjdk.org/panama-foreign/pull/844/files
 Webrev: https://webrevs.openjdk.org/?repo=panama-foreign&pr=844&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311594
  Stats: 242 lines in 3 files changed: 242 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/panama-foreign/pull/844.diff
  Fetch: git fetch https://git.openjdk.org/panama-foreign.git pull/844/head:pull/844

PR: https://git.openjdk.org/panama-foreign/pull/844