RFR(S): 8247529: Crash in runtime/cds/appcds/dynamicArchive/LambdaProxyCallerIsHidden.java with Graal

[calvin.cheung at oracle.com]

bug: https://bugs.openjdk.java.net/browse/JDK-8247529
webrev: http://cr.openjdk.java.net/~ccheung/jdk16/8247529/webrev.00/

This proposed change includes:

1) Avoid inserting InstanceKlass into the DumpTimeSharedClassTable after 
dynamic CDS dumping has started.

This is done by adding a _dump_in_progress bool which will be set at the 
beginning of dynamic CDS dumping. In 
DumpTimeSharedClassTable::find_or_allocate_info_for, if the 
_dump_in_progress is set, it will not create a new entry in the table.

2) Acquire the DumpTimeTable_lock before iterations on _dumptime_table 
to ensure memory order correctness.

Testing: passed tier1 - 4 tests.

thanks,

Calvin