RFR: 8233343: Deprecate -XX:+CriticalJNINatives flag which implements Java… [v2]

[Coleen Phillimore]

> This change deprecates the -XX:+CriticalJNINatives flag and removes the develop flag -XX:+StressCriticalJNINatives.  See CSR for more details.
> 
> This change also removes the lazy GC lock in the critical native transition, and runs the critical native function as thread_in_Java.  I add a safepoint check at the end of the native function and transition to native and poll again for the safepoint after the function if a safepoint is requested.
> 
> Tested with tier 1-6 (we have a few tests that use this).  And built on linux-x86-open,linux-s390x-open,linux-arm32-debug,linux-ppc64le-debug.

Coleen Phillimore has updated the pull request incrementally with two additional commits since the last revision:

 - Fixed test to run on other platforms, fixed copyrights, fixed ppc code.
 - Remove pin/unpin object code.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/764/files
  - new: https://git.openjdk.java.net/jdk/pull/764/files/fa23ec19..847feca7

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=764&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=764&range=00-01

  Stats: 280 lines in 9 files changed: 5 ins; 269 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/764.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/764/head:pull/764

PR: https://git.openjdk.java.net/jdk/pull/764