manifest: skip MYMETA.*
fix global destruction order bug

Per Process singleton objects are not always destroyed due to the fact
that global destruction happens in an unpredictable order.

Work around based on Class::Singleton proposed patch from Steve Hay that
uses a package hash to hold the instances, and undefs it with an END
block. [#68534]
v0.16

    - fix signature test due to MYMETA.* in new EU::MM
    - Work around global destruction order issue by integrating on proposed
      patch to Class::Singleton [#68534] (Thanks Steve Hay!)