Enable compact object headers on Java 24+

[OowhitecatoO]

This is the small follow-up I mentioned in #4205. Upstream MeowIce has added -XX:+UseCompactObjectHeaders since the flag set was copied into the image, and of everything that changed it is the one worth picking up on its own.

It is gated on Java 24 or newer because the option does not exist before that, and an unrecognised -XX: option is fatal — emitting it unconditionally would stop USE_MEOWICE_FLAGS from starting on the java17 and java21 images. Upstream now says its flags target Java 25+, but the image applies MeowIce's set from 17 upwards, so the gate has to live here.

The other differences from upstream are less clear-cut, so I have left the rest of the set alone.

Details, if useful

What it does: JEP 450 folds the class pointer into the mark word, so an object header is 8 bytes instead of 12 plus padding. Allocating 5,000,000 new Object() into a reachable array in a 2G heap:

	heap used after a full GC
-XX:-UseCompactObjectHeaders	99 MB
-XX:+UseCompactObjectHeaders	61 MB

The 5M-element Object[] accounts for about 19 MiB of that on both sides, so the objects themselves go from roughly 16 bytes to 8.

Version compatibility:

Java	flag
17, 21	does not exist — fatal
24	{experimental}, default false
25	{product}, default false

On 24 it has to be preceded by -XX:+UnlockExperimentalVMOptions, which the block already emits well before this point.

Verified by generating the flag set with USE_MEOWICE_FLAGS and starting a JVM with it on each version:

image	UseCompactObjectHeaders emitted	java -version
eclipse-temurin:17-jre	no	rc=0
eclipse-temurin:21-jre-noble	no	rc=0
eclipse-temurin:24-jre	yes	rc=0
eclipse-temurin:25-jre-noble	yes	rc=0

[itzg]

Thanks!