RFR: JDK-8162340: Better class stream parsing

[Karen Kinnear]

Please review:
https://bugs.openjdk.java.net/browse/JDK-8162340

http://cr.openjdk.java.net/~acorn/8162340.hs/webrev/
http://cr.openjdk.java.net/~acorn/8162340.jdk.test/webrev

When moving the check from resolve_from_stream to set_package, I removed
the no longer need parsed_class (!) which I should have cleaned up when
tightening the placeholder table cleanup years ago.

Tests run:
1. updated VMAnonymousClass test
2. jcks
3. rbt hs-nightly-runtime linux-x64 in progress

thanks,
Karen