Fix GC metadata in support functions and follow the new invalid args ABI.
Fix GC metadata in support functions and follow the new invalid args ABI.

The previous GCMD did not properly represent stack arguments, but this
could only occur if the functions were called with the wrong number
of arguments.

froggey/Mezzano,rvedam/Mezzano,rvedam/Mezzano,froggey/Mezzano