address compiler warnings
Description
This MR clean-ups the code and addresses a few compiler warnings:
- Disable pointer to int conversion if cuda is missing
- Remove unused
pnfft_oct_m
fromcube_oct_m
module - Disable code paths if PNFFT is missing
- Initialize variables if PNFFT is missing
- Disable unused subroutine
opt_control_nlopt_func
if NLOPT is missing - Disable unused variable
cf
if ETSF_IO is missing
Edited by Meisam Tabriz