Replace os::glob with extra::glob, which is written in rust,

fixing issue #6100.

Author: Dretch

src/libextra/extra.rs

@@ -85,6 +85,7 @@ pub mod getopts;
 pub mod json;
 pub mod md4;
 pub mod tempfile;
+pub mod glob;
 pub mod term;
 pub mod time;
 pub mod arena;