Deprecation of 0 as a null pointer constant

[alejandro-colomar]

GCC 15 will add -Wzero-as-null-pointer-constant working towards the deprecation of 0 as a null pointer constant in C. Let's remove all of our uses of 0 as a null pointer constant already.

I'm also working on a paper for deprecating it in ISO C2y.

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117059
Link: https://software.codidact.com/posts/292718/292759#answer-292759