[foreign-abi] RFR: 8228762: import CallingSequenceBuilder unit tests

[Nick Gasson]

Hi Maurizio,

> Looks good, but I'm a bit puzzled by the ArgumentClassTest; in general
> the test seems pretty obscure - but there's also the problem that the
> test is ultimately SysV specific, so it will only stress the
> ArgumentClassImpl specific to SysV. Not sure this test is robust enough
> (as the other) to make the cut, to be honest.
> 
> What do you think?
> 

This one got included because I took the whole test/jdk/foreign/abi 
directory from the foreign branch. I agree it's not as useful as the 
main CallingSequenceTest which should test the merge method indirectly 
anyway. I'm happy to take it out of this patch if Jorn agrees too? (I 
think he added it originally.)


Nick