Memory Safety: Medium
In new_setup_simd(), the return value of malloc() for the PFFFT_Setup
struct was not checked before dereferencing. Similarly,
pffft_aligned_malloc() for the data buffer was not checked. If either
allocation fails, the code dereferences NULL causing a crash.
Add NULL checks for both allocations, freeing previously allocated
memory on failure.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>