Zig asserts are not C asserts

With the common case of SimplifyCFG turning this into an assumption (for ReleaseFast), this is UB (LLVM def) unless you can prove that the assumption always holds.

I suppose that's par for the course with an unchecked release build, but at the same time memory corruption is much easier to debug as compared to 'the compiler changed the logic of my program in strange/incorrect ways'.