JVMCI 21.0-b03 release

[Doug Simon]

This release includes:

	• GR-27678: Added JVMCICompiler.isGCSupported and made use of it in WhiteBox API (JDK-8257020).
	• JDK-8257220: [JVMCI] option validation should not result in a heavy-weight VM crash.
	• JDK-8250233: -XX:+CITime triggers guarantee(events != NULL) in jvmci.cpp:173.

The OpenJDK based Windows, Linux and macOS binaries are available at:

https://github.com/graalvm/graal-jvmci-8/releases/tag/jvmci-21.0-b03
https://github.com/graalvm/labs-openjdk-11/releases/tag/jvmci-21.0-b03
https://github.com/graalvm/labs-openjdk-15/releases/tag/jvmci-21.0-b03

-Doug