fix compile-fail tests

Author: nikomatsakis

src/test/compile-fail/issue-25439.rs

@@ -15,5 +15,5 @@ fn fix<F>(f: F) -> i32 where F: Fn(Helper<F>, i32) -> i32 {
 }
 
 fn main() {
-    fix(|_, x| x); //~ ERROR mismatched types
+    fix(|_, x| x); //~ ERROR closure/generator type that references itself [E0644]
 }

src/test/compile-fail/occurs-check-2.rs

@@ -16,7 +16,5 @@ fn main() {
     g = f;
     f = box g;
     //~^  ERROR mismatched types
-    //~| expected type `_`
-    //~| found type `std::boxed::Box<_>`
     //~| cyclic type of infinite size
 }

src/test/compile-fail/occurs-check.rs

@@ -14,7 +14,5 @@ fn main() {
     let f;
     f = box f;
     //~^ ERROR mismatched types
-    //~| expected type `_`
-    //~| found type `std::boxed::Box<_>`
     //~| cyclic type of infinite size
 }