make tests/utils work with edition 2015

Author: RalfJung

src/tools/miri/tests/utils/mod.rs

@@ -7,8 +7,8 @@ mod macros;
 mod fs;
 mod miri_extern;
 
-pub use fs::*;
-pub use miri_extern::*;
+pub use self::fs::*;
+pub use self::miri_extern::*;
 
 pub fn run_provenance_gc() {
     // SAFETY: No preconditions. The GC is fine to run at any time.