RFR: 8043275 8u40 backport: Interface initialization for default methods

[Karen Kinnear]

Please review 8u40 backport:

webrev: http://cr.openjdk.java.net/~acorn/8043275.8u40/webrev/
bug: https://bugs.openjdk.java.net/browse/JDK-8043275

Summary:
 Fix superinterface initialization to be based on declaring a non-static instance method rather than
on declaring or inheriting one

Tested (linux-x64) 8u40:
jtreg hotspot lambda-features which includes the two new tests: TestInterfaceInit and TestInterfaceOrder
InvokespecialInterface was changed to use nested classes so there is no name conflict for C.class in that directory

thanks,
Karen