librustc: Fix cross-crate reexports. rs=blocking-servo

src/test/auxiliary/pub_use_mods_xcrate.rs

@@ -0,0 +1,11 @@
+pub mod a {
+    pub mod b {
+        pub mod c {
+            fn f(){}
+            fn g(){}
+        }
+    }
+
+    pub use b::c;
+}
+

src/test/run-pass/pub_use_mods_xcrate_exe.rs

@@ -0,0 +1,8 @@
+// xfail-fast
+// aux-build:pub_use_mods_xcrate.rs
+
+extern mod pub_use_mods_xcrate;
+use pub_use_mods_xcrate::a::c;
+
+fn main(){}
+