Disable all warnings seen on devkitA64 GCC 15.1.0:
- Several false-positive `-Wmisleading-indentation` warnings (the
indentation is not actually misleading)
- One `-Wuse-after-free` warning, which looks alarming and represents
very dubious design, but is ultimately harmless (a freed pointer is
passed to a function that doesn't use it).
- Some `-Wunused-function` warnings in `simd/neon.h`