Add JNI_VERSION_19 for Java 19+

[keithc-ca]

See:

• 8286176: Add JNI_VERSION_19 to jni.h and JNI spec

Also a little tidying up: mostly trailing whitespace.

[pshipton]

jenkins compile amac jdk19

[pshipton]

@tajila fyi

[pshipton]

@keithc-ca it didn't actually work, JNI_VERSION_19 didn't show up in the build. Perhaps we aren't defining JAVA_SPEC_VERSION properly yet?

[keithc-ca]

I explicitly looked for and found it in vm/runtime/include/jni.h.
I'll investigate why that didn't make it into the jdk image.

[pshipton]

Actually, we use the OpenJDK version in the builds. I'm assuming the jdk19 change hasn't promoted yet.

[keithc-ca]

It appears that jni.h is a copy from upstream; when 8286176: Add JNI_VERSION_19 to jni.h and JNI spec gets promoted to the openj9 branch we should see JNI_VERSION_19 defined.

CopyCommon.gmk is responsible for copying that file. So we don't have a real problem other than ensuring that OpenJ9 (mostly test?) code sees a consistent copy of jni.h.

[keithc-ca]

I'm inclined to adjust the build of OpenJ9 to use that file from upstream instead of the one defined by this repo.

[pshipton]

I think the OpenJ9 jni.h is only used for IBM Java 8.