Move /src/test to /tests

tests/ui/array-slice-vec/subslice-only-once-semantic-restriction.rs

@@ -0,0 +1,11 @@
+fn main() {
+    let a: &[u8] = &[];
+    match a {
+        [1, tail @ .., tail @ ..] => {},
+        //~^ ERROR identifier `tail` is bound more than once in the same pattern
+        //~| ERROR `..` can only be used once per slice pattern
+        _ => ()
+    }
+}
+
+const RECOVERY_WITNESS: () = 0; //~ ERROR mismatched types