RFR 8152295: Redundant CLCs for classes resolved in both loaders

[harold seigel]

Hi,

Please review this JDK-10 change to not record loader constraints if 
both class loader classes are the same.  This change reduces the number 
of recorded loader constraints when running the Queens program from six 
to four.  It reduces the number of recorded loader constraints when 
running javac to compile Queens.java from 110 to 55.

Additionally, the logging code for LaderConstraintTable::add_entry() was 
restructured to simplify things and improve readability.

Open Webrev: http://cr.openjdk.java.net/~hseigel/bug_8152295/webrev/

JBS Bug: https://bugs.openjdk.java.net/browse/JDK-8152295

The fix was tested with JCK Lang and VM tests, the JTreg hotspot, 
java/io, java/lang, java/util and other tests, the co-located NSK tests, 
RBT tests, and with JPRT.

Thanks, Harold