RFR (s) 8047736: Remove JVM_GetClassLoader as no longer used

[Coleen Phillimore]

Summary: Remove this function from hotspot.  It's already removed from 
the JDK.

Related to the bug I just fixed in the change I made months ago, the JVM 
interface to get the classLoader of a java/lang/Class is no longer 
needed.  This change has been approved by Oracle's licensees and has 
been approved in the internal compatibility committee request.

Tested with nsk testbase and jtreg regression tests.

open webrev at http://cr.openjdk.java.net/~coleenp/8047736/
bug link https://bugs.openjdk.java.net/browse/JDK-8047736

Thanks,
Coleen