[foreign] RFR 8211275: Binder should check that signature of bound function is compatible with layout descriptions

[Maurizio Cimadamore]

Hi,
this is a RFR for the changes discussed in [1] (thanks Jorn!). I've 
added few things:

* ensure that callbacks are checked too

* refactored the isCompatible method to be more usable from clients 
(e.g. reuse logic that throws assertions)

* added one more testcase to check a simple case of callback mismatch, 
just to make sure the logic is executed

Webrev:

http://cr.openjdk.java.net/~mcimadamore/panama/8211275/

Cheers
Maurizio

[1] - 
http://mail.openjdk.java.net/pipermail/panama-dev/2018-September/002786.html