mesa: sort state vars with constant indexing for ARB programs

mesa: sort state vars with constant indexing for ARB programs

This enables merging of state variables such as local parameters
for faster constant uploads. For Trine 2, this mainly sorts local
parameters which are in a random order.

Originally, the next pass added state variables (the code after this code).
If we add them before that, _mesa_add_state_reference will be a no-op
later and will return the ones we added.

So add all state parameters (without indirect indexing). After they are
added, sort them within the parameter list. Then fix their offsets to
correspond to their location after sorting.

Reviewed-by: Zoltán Böszörményi <zboszor@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8183>