Function mi_theap_zalloc_small 

pub unsafe extern "C" fn mi_theap_zalloc_small(
    theap: *mut mi_theap_t,
    size: usize,
) -> *mut c_void

Equivalent to mi_heap_zalloc_small, but for a thread-local heap (theap) in v3.

size must be smaller or equal to MI_SMALL_SIZE_MAX.