Currently, java.lang.invoke.VarHandles$GuardMethodGenerator is in a weird state: when VarHandleGuards needs to be updated, we uncomment it, build JDK, run it as a main class, and paste the generated VarHandleGuards class.

This process is error-prone, and having a huge chunk of commented out code is not good for maintenance and verification too.

Looking at how i18n and charsets generate, we can move this generator to the build system, and have VarHandleGuards completely automatically generated like the other VarHandle implementation classes or CharacterData.