Remove unnecessary allocation in non-integral reference code

[AndrewWestberg]

Description

Temp variables in ref_exp_ function are never used. They are just allocated and cleared. Since this is a recursive function and the reference code serves as a baseline for performance, it should be fixed.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• Self-reviewed the diff

[lehins]

Nice catch.

Looks like the original version did use those temporary variables, but then usage was removed in e73df76

Note that that there are variables temp_q and temp_r that are used in the second half of the function, but they are defined, initialized and cleared separately, so these two that are being removed are definitely unused

Thank you.