fix clippy ==0 be replaced is_empty()

Created by: honeywest

warning: length comparison to zero --> build.rs:104:19 | 104 | } else if name.as_os_str().len() != 0 { | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: using !is_empty is clearer and more explicit: !name.as_os_str().is_empty()

ok_or be replaeced ok_or_else. You do it, or I'll do it when I have time.