RFR: 8256746: gc/CriticalNativeArgs.java fails without -XX:-CriticalJNINatives

[Aleksey Shipilev]

Found this with Zero testing, but the failure is not Zero-specific. It affects platforms that do not have `CriticalJNINatives` enabled. The issue is that the fallback (non-critical) native version of the code calls `GetArrayLength` on known `NULL` array.

$ CONF=linux-x86_64-zero-fastdebug make exploded-test TEST=gc/CriticalNativeArgs.java
#
# Internal Error (/home/shade/trunks/jdk/src/hotspot/share/runtime/jniHandles.inline.hpp:91), pid=1909139, tid=1909217
# assert(handle != __null) failed: JNI handle should not be null

It was exposed by [JDK-8233343](https://bugs.openjdk.java.net/browse/JDK-8233343) that added the generic test configuration, and then by [JDK-8256499](https://bugs.openjdk.java.net/browse/JDK-8256499) that enabled Zero+Epsilon. Before that, the test was only enabled for specific GCs and arches where `CriticalJNINatives` are known to work, and thus we never took that (broken) fallback in this test.

Note that `CriticalJNINatives` is a deprecated flag, and I expect the test to go away together with the flag later. Meanwhile, let's make sure it runs properly. I also reformatted the run configs a bit to make them more readable, and added `-XX:-CriticalJNINatives` to expose the affected path in most configurations.

Additional testing:
 - [x] Affected test with Zero (+Epsilon, +Shenandoah)
 - [x] Affected test with Server (+Epsilon, +Shenandoah)

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

Commit messages:
 - 8256746: gc/CriticalNativeArgs.java fails without -XX:-CriticalJNINatives

Changes: https://git.openjdk.java.net/jdk/pull/1349/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1349&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8256746
  Stats: 46 lines in 2 files changed: 36 ins; 2 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1349.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1349/head:pull/1349

PR: https://git.openjdk.java.net/jdk/pull/1349