r9347: this array bounds checking is harder than it looks ...

r9347: this array bounds checking is harder than it looks ...

this copes with 2 more situations:

1) where the array is NULL, which would previously be coped with by a
   if (ptr) check, but now in the deferred array bounds checking needs
   to look at the array variable in the ndr code. Not nice.

2) nest the array checking along with the SCALARS vs BUFFERS checks, ensuring we don't
   do array bounds checking for a buffer when in scalars only mode