GCC 14 is quite picky about warnings, probably more so than clang.
-Fix a bunch of printf warnings. Pointers should be printed with %p.
-Move some stuff into an anonymous namespace.
-Worked around GCC really not liking reinterpret_casting from one
function pointer type to another. Fiddled with it a bit and eventually
settled on casting the function pointer to const void * and passing it
through.
