[8u40] RFR 6642881: Improve performance of Class.getClassLoader()

[Coleen Phillimore]

Summary: Add classLoader to java/lang/Class instance for fast access

This is a backport request for 8u40.   This change has been in the jdk9 
code for 3 months without any problems.

The JDK changes hg imported cleanly.  The Hotspot change needed a hand 
merge for create_mirror call in klass.cpp.

http://cr.openjdk.java.net/~coleenp/6642881_8u40_jdk/
http://cr.openjdk.java.net/~coleenp/6642881_8u40_hotspot/

bug link https://bugs.openjdk.java.net/browse/JDK-6642881

Ran jdk_core jtreg tests in jdk with both jdk/hotspot changes. Also ran 
jck java_lang tests with only the hotspot change.  The hotspot change 
can be tested separately from the jdk change (but not the other way around).

Thanks,
Coleen