RFR(S) 8193332 MetaspaceShared::check_shared_class_loader_type is not used during archive creation

[Ioi Lam]

https://bugs.openjdk.java.net/browse/JDK-8193332
http://cr.openjdk.java.net/~iklam/jdk11/8193332-check_shared_class_loader_type.v01/

Summary:

When we restructured the AppCDS code, the call to 
MetaspaceShared::check_shared_class_loader_type
was somehow left out. I have restored it, and actually found a minor bug 
related to modules
and -Xbootclasspath/a:

In classLoader.cpp, at dump time we used to load a class from 
-Xbootclasspath/a even if
this class belongs to a named packaged, which means it would not be 
loaded by the JVM at runtime.
Such dump-time loading seems unnecessary so I removed it, and fixed a 
related test case
to reflect the latest behavior.

Tested with hs-tier1,2.

Thanks
- Ioi