RFR (T) 8250519: [REDO] Move mirror oops from Universe into OopStorage

[coleen.phillimore at oracle.com]

Summary: The original patch but add a null pointer check so an OopHandle 
is not created if a NULL is read from the archive.

If a NULL is read from the archive, we shouldn't create an OopHandle for 
it because one will be created in initialize_basic_type_mirrors.  The 
assert added in the previous patch I pushed detected that.

incremental change to original change: 
http://cr.openjdk.java.net/~coleenp/2020/8250519.01.incr/webrev
full webrev at http://cr.openjdk.java.net/~coleenp/2020/8250519.01/webrev

Retested with tier1-3.

Thanks,
Coleen