No implementations actually modify instance state (and it would be
questionable to do that in the first place given the name), so we can
make this a const member function.
A process should never require being reference counted in this
situation. If the handle to a process is freed before this function is
called, it's definitely a bug with our lifetime management, so we can
put the requirement in place for the API that the process must be a
valid instance.
An instance of the NAX apploader already has an existing NAX instance in
memory. Calling directly into IdentifyType() directly would re-parse the
whole file again into yet another NAX instance, only to toss it away
again.
This gets rid of unnecessary/redundant file parsing and allocations.
