check and adjust FFT selection for KOKKOS depending on whether CUDA is enabled or not

#include "remap_kokkos.h"

#include "fftdata_kokkos.h"

// with KOKKOS in CUDA mode we can only have

// CUFFT or KISSFFT, thus undefine all other

// FFTs here, since they may be valid in fft3d.cpp

#if defined(KOKKOS_ENABLE_CUDA)

# if defined(FFT_FFTW)

#  undef FFT_FFTW

# endif

# if defined(FFT_FFTW3)

#  undef FFT_FFTW3

# endif

# if defined(FFT_MKL)

#  undef FFT_MKL

# endif

# if !defined(FFT_CUFFT) && !defined(FFT_KISSFFT)

#  define FFT_KISSFFT

# endif

#else

# if defined(FFT_CUFFT)

#  error "Must enable CUDA with KOKKOS to use -DFFT_CUFFT"

# endif

#endif

// if user set FFTW, it means FFTW3

#ifdef FFT_FFTW

#define FFT_FFTW3

#endif

#ifdef FFT_FFTW_THREADS

#if !defined(FFT_FFTW3)

#error "Must use -DFFT_FFTW3 with -DFFT_FFTW_THREADS"