make the test only deal with edition flags

src/test/ui/crate-in-paths.rs

@@ -8,8 +8,9 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(crate_visibility_modifier)]
-#![feature(crate_in_paths)]
+// edition:2018
+
+#![feature(edition_2018_preview)]
 
 mod bar {
     crate struct Foo;

src/test/ui/crate-in-paths.stderr

@@ -1,5 +1,5 @@
 error[E0425]: cannot find value `Foo` in this scope
-  --> $DIR/crate-in-paths.rs:19:5
+  --> $DIR/crate-in-paths.rs:20:5
    |
 LL |     Foo;
    |     ^^^ not found in this scope