Auto merge of #26253 - steveklabnik:remove_old_ignored_tests, r=brson

Two commits here: one which removes a bunch of tests, and re-enables a few that work.

Second updates the syntax of one of the failing tests. It still doesn't pass, but at least it compiles.

Author: bors

src/test/compile-fail/dead-code-closure-bang.rs

@@ -15,5 +15,5 @@
 fn main() {
     let x = || panic!();
     x();
-    std::io::println("Foo bar"); //~ ERROR: unreachable statement
+    println!("Foo bar"); //~ ERROR: unreachable statement
 }

src/test/compile-fail/issue-15167.rs

@@ -9,11 +9,6 @@
 // except according to those terms.
 
 // macro f should not be able to inject a reference to 'n'.
-//
-// Ignored because `for` loops are not hygienic yet; they will require special
-// handling since they introduce a new pattern binding position.
-
-// ignore-test
 
 macro_rules! f { () => (n) }