Add must-compile-successfully comment to appropriate ui tests.

src/test/ui/codemap_tests/unicode_3.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// must-compile-successfully
+
 fn main() {
     let s = "ZͨA͑ͦ͒͋ͤ͑̚L̄͑͋Ĝͨͥ̿͒̽̈́Oͥ͛ͭ!̏"; while true { break; }
     println!("{}", s);