Function libevent_sys::event_set_mem_functions

pub unsafe extern "C" fn event_set_mem_functions(
    malloc_fn: Option<unsafe extern "C" fn(sz: size_t) -> *mut c_void>,
    realloc_fn: Option<unsafe extern "C" fn(ptr: *mut c_void, sz: size_t) -> *mut c_void>,
    free_fn: Option<unsafe extern "C" fn(ptr: *mut c_void)>
)