tests: Move run-pass tests without naming conflicts to ui

src/test/ui/for-loop-while/foreach-external-iterators.rs

@@ -0,0 +1,10 @@
+// run-pass
+
+pub fn main() {
+    let x = [1; 100];
+    let mut y = 0;
+    for i in &x[..] {
+        y += *i
+    }
+    assert_eq!(y, 100);
+}