Add java.lang.Access.allowSecurityManager to jdk21

[pshipton]

Closes #20748

[pshipton]

Set as draft as it needs to be merged concurrently with jdk21 openj9-staging promotion.

[pshipton]

Once we get a review approval on this, we can run the equivalent of the acceptance build.

[JasonFengJ9]

openj9/jcl/src/java.base/share/classes/java/lang/System.java

Lines 1304 to 1308 in f8939d1

	/*[IF JAVA_SPEC_VERSION == 23]*/
	static boolean allowSecurityManager() {
	return !throwUOEFromSetSM;
	}
	/*[ENDIF] JAVA_SPEC_VERSION == 23 */

System.allowSecurityManager() is needed for JDK21.

[pshipton]

Right... updated.

[JasonFengJ9]

LGTM

[pshipton]

jenkins test sanity all jdk21 depends ibmruntime/openj9-openjdk-jdk21#openj9-staging

[keithc-ca]

The aarch64_linux build encountered what looked like an infrastructure problem: I restarted it.