RFR: 8286669: Replace MethodHandle specialization with ASM in mainline

[Jorn Vernee]

Hi,

This PR brings over commits from the panama-foreign repo. These commits mostly pertain to the switch to ASM and away from MethodHandle combinators for the binding recipe specialization. But, there is one more commit which adds freeing of downcall stubs, since those changes were mostly Java as well.

Thanks,
Jorn

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Depends on: https://git.openjdk.java.net/jdk/pull/7959

Commit messages:
 - Fix LinkUpcall benchmark
 - 8286306: Upcall wrapper class sharing
 - Polish
 - 8281595: ASM-ify scope acquire/release for down call parameters
 - 8281228: Preview branch's CLinker.downcallHandle crashes inside asm
 - 8278414: Replace binding recipe customization using MH combinators with bytecode spinning
 - 8276648: Downcall stubs are never freed

Changes: https://git.openjdk.java.net/jdk/pull/8685/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8685&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8286669
  Stats: 2171 lines in 24 files changed: 1384 ins; 660 del; 127 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8685.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8685/head:pull/8685

PR: https://git.openjdk.java.net/jdk/pull/8685