i965: Allow old begin/end queryobj for gen4/5 with HW contexts

i965: Allow old begin/end queryobj for gen4/5 with HW contexts

Since we have HW contexts on gen4/5, we could take advantage of them, as
done for gen6+ in commit e32cd5ffbb72 ("i965: Rely on hardware contexts
for query objects on Gen6+."), to only emit a pair of counters at
begin/end queryobj, rather than around every primitive. However, to keep
queryobj working in the meantime as we bringup support for HW ctx on
gen4/5, we can keep using the existing code.

References: e32cd5ffbb72 ("i965: Rely on hardware contexts for query objects on Gen6+.")
Cc: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>