Fix feature flag confusion in source.rs for Windows build

Author: sdroege

src/source.rs

@@ -4,7 +4,7 @@
 
 use std::cell::RefCell;
 use std::mem::transmute;
-#[cfg(any(unix, feature = "dox"))]
+#[cfg(unix)]
 use std::os::unix::io::RawFd;
 #[cfg(all(not(unix), feature = "dox"))]
 use libc::c_int as RawFd;