test: Move missing-items to a ui test

This test is failing on nightly for unknown reasons, and my best guess is a
difference in grep versions which is interpreting symbols differently. For now
let's just move this to a ui test and hope it fixes nightlies.

src/test/run-make/missing-items/m1.rs → src/test/ui/missing-items/auxiliary/m1.rs

@@ -9,9 +9,9 @@
 // except according to those terms.
 
 #![feature(associated_consts)]
-#![crate_type = "dylib"]
+
 pub trait X {
-  const CONSTANT: u32;
-  type Type;
-  fn method(&self, s: String) -> Self::Type;
+    const CONSTANT: u32;
+    type Type;
+    fn method(&self, s: String) -> Self::Type;
 }

src/test/run-make/missing-items/m2.rs → src/test/ui/missing-items/m2.rs

@@ -8,8 +8,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// aux-build:m1.rs
+
 #![feature(associated_consts)]
-#![crate_type = "dylib"]
+
 extern crate m1;
 
 struct X {

src/test/ui/missing-items/m2.stderr

@@ -0,0 +1,14 @@
+error: main function not found
+
+error[E0046]: not all trait items implemented, missing: `CONSTANT`, `Type`, `method`
+  --> $DIR/m2.rs:20:1
+   |
+20 | impl m1::X for X {
+   | ^ missing `CONSTANT`, `Type`, `method` in implementation
+   |
+   = note: `CONSTANT` from trait: `const CONSTANT: u32;`
+   = note: `Type` from trait: `type Type;`
+   = note: `method` from trait: `fn(&Self, std::string::String) -> <Self as m1::X>::Type`
+
+error: aborting due to previous error
+