[foreign-abi] RFR 8237360: Add tests that test binding recipe generation directly

[Jorn Vernee]

Hi,

Please review the following patch that adds tests for the binding recipe 
generators. These tests are more or less transcribed from the old 
CallingSequenceBuilder tests on the foreign branch.

Bug: https://bugs.openjdk.java.net/browse/JDK-8237360
Webrev: 
http://cr.openjdk.java.net/~jvernee/panama/webrevs/8237360/webrev.00/

This also helped me find a couple of bugs in the Aarch64 CallArranger 
that I introduced in an earlier patch, which I've fixed.

Thanks,
Jorn