An LLM will also give the same output for the same input when the temperature is zero[1]. It only becomes non-deterministic if you choose for it to be. Which is the same for a C compiler. You can choose to add as many random conditionals as you so please.
But there is nothing about a compiler that implies determinism. A compiler is defined by function (taking input on how you want something to work and outputting code), not design. Implementation details are irrelevant. If you use a neural network to compile C source into machine code instead of more traditional approaches, it most definitely remains a compiler. The function is unchanged.
[1] "Faulty" hardware found in the real world can sometimes break this assumption. But a C compiler running on faulty hardware can change the assumption too.
