nv50: add compute invocations counter

nv50: add compute invocations counter

This is a purely software counter alongside the other hardware counters
for ease of use and consistency. However we have to make room for it in
the allocated query space. Use this opportunity to make the nv50 queries
work like the nvc0 ones in terms of space allocation.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Pierre Moreau <dev@pmoreau.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10164>