Remove compile-pass from error codes' explanation

Author: JohnTitor

src/librustc_mir/error_codes.rs

@@ -331,7 +331,7 @@ An if-let pattern attempts to match the pattern, and enters the body if the
 match was successful. If the match is irrefutable (when it cannot fail to
 match), use a regular `let`-binding instead. For instance:
 
-```compile_pass
+```
 struct Irrefutable(i32);
 let irr = Irrefutable(0);
 
@@ -360,7 +360,7 @@ A while-let pattern attempts to match the pattern, and enters the body if the
 match was successful. If the match is irrefutable (when it cannot fail to
 match), use a regular `let`-binding inside a `loop` instead. For instance:
 
-```compile_pass,no_run
+```no_run
 struct Irrefutable(i32);
 let irr = Irrefutable(0);