malloc(0)

The null pointer satisfies all of the technical requirements of a heap-allocated zero-length array (you can form a pointer that is one past the end, you can iterate over it zero times with a standard for loop, and you can pass it to realloc without breaking anything), and all heap-allocated zero-length arrays are functionally identical because they have no state which can be mutated, so returning NULL can be thought of as semantically equivalent to a copy elision (i.e. you could think of all heap-allocated zero-length arrays as "copies" of the zero-length array that lives at NULL, and then you can elide those copies because zero-length arrays are immutable, so making a copy is unnecessary).

The fact that it happens to vaguely resemble some feature of Lisp, but the standard does not actually require it to fulfill all the requirements of that feature is, frankly, Lisp's problem, not C's problem.