Fix a compilation error on windows

Author: brson

src/compiletest/procsrv.rs

@@ -14,7 +14,7 @@ fn target_env(lib_path: ~str, prog: ~str) -> ~[(~str,~str)] {
     let aux_path = prog.slice(0u, prog.len() - 4u) + ~".libaux";
 
     env = do vec::map(env) |pair| {
-        let (k,v) = pair;
+        let (k,v) = *pair;
         if k == ~"PATH" { (~"PATH", v + ~";" + lib_path + ~";" + aux_path) }
         else { (k,v) }
     };