webrev to fix some assert logic in the hsail argument-gathering code

[Deneau, Tom]

I have posted a small webrev to fix some assert logic in the argument-gathering code that shows up when non-product hotspot builds are done with the new "run hsail kernels in hotspot" logic.
 
http://cr.openjdk.java.net/~tdeneau/graal-webrevs/webrev-okrahotspot-assert-fixes/webrev/ 

Summary:
    * computes parameter_count based on signature and uses that and parameter_index (set by the SignatureIterator) to tell if we are on the last parameter, which requires special handling whether it is an int or an object.
    * 	if signature says last parameter is an Object, checks that the real passed in parameter is an Object Array, but for non last-parameters, lets  objects go thru.
    *	if signature says last parameter is an int, nothing is pushed (no change to this logic)


-- Tom