Cleaned up some tests

Split invalid-compile-flags into run-pass & invalid

Update tests/ui/README.md

Author: reddevilmidzy

tests/ui/README.md

@@ -1,6 +1,7 @@
+//! regression test for issue https://github.com/rust-lang/rust/issues/46472
 fn bar<'a>() -> &'a mut u32 {
     &mut 4
     //~^ ERROR cannot return reference to temporary value [E0515]
 }
 
-fn main() { }
+fn main() {}

tests/ui/borrowck/return-ref-to-temporary.rs

@@ -1,5 +1,5 @@
 error[E0515]: cannot return reference to temporary value
-  --> $DIR/issue-46472.rs:2:5
+  --> $DIR/return-ref-to-temporary.rs:3:5
    |
 LL |     &mut 4
    |     ^^^^^-

tests/ui/borrowck/return-ref-to-temporary.stderr

@@ -7,8 +7,9 @@
 // reasonable examples) let to ambiguity errors about not being able
 // to infer sufficient type information.
 
-
 fn main() {
     let n = 0;
-    let it = Some(1_usize).into_iter().inspect(|_| {n;});
+    let it = Some(1_usize).into_iter().inspect(|_| {
+        n;
+    });
 }

tests/ui/closures/closure-upvar-trait-caching.rs

@@ -1,4 +1,5 @@
+//! regression test for https://github.com/rust-lang/rust/issues/24779
 //@ run-pass
 fn main() {
-    assert_eq!((||||42)()(), 42);
+    assert_eq!((|| || 42)()(), 42);
 }