Add PWR082: Remove unused variables

[alvrogd]

Add entry and benchmark for a new check. My results:

$ lscpu
  Model name:             13th Gen Intel(R) Core(TM) i7-13700H

$ gcc --version                            
gcc (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0

$ gfortran --version                                                 
GNU Fortran (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0

$ python3 run-benchmarks.py --check PWR083
------------------------------------------------------------------
Benchmark                        Time             CPU   Iterations
------------------------------------------------------------------
PWR082 C Example               435 us          435 us         1601
PWR082 C Improved              435 us          435 us         1603
PWR082 Fortran Example         430 us          430 us         1622
PWR082 Fortran Improved        429 us          429 us         1634