Function transmission_sys::tr_strndup

pub unsafe extern "C" fn tr_strndup(
    in_: *const c_void, 
    len: usize
) -> *mut c_char

@brief make a newly-allocated copy of a substring @param in is a void* so that callers can pass in both signed & unsigned without a cast @param len length of the substring to copy. if a length less than zero is passed in, strlen(len) is used @return a newly-allocated copy of `in' that can be freed with tr_free()