Update ui tests

Author: GuillaumeGomez

src/test/ui/auto-trait-validation.stderr

@@ -18,5 +18,5 @@ LL | auto trait MyTrait { fn foo() {} }
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0380, E0567.
+Some errors have detailed explanations: E0380, E0567, E0568.
 For more information about an error, try `rustc --explain E0380`.

src/test/ui/traits/traits-inductive-overflow-supertrait-oibit.stderr

@@ -17,4 +17,5 @@ LL |     let (a, b) = copy(NoClone);
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0277`.
+Some errors have detailed explanations: E0277, E0568.
+For more information about an error, try `rustc --explain E0277`.

src/test/ui/typeck/typeck-auto-trait-no-supertraits-2.stderr

@@ -6,3 +6,4 @@ LL | auto trait Magic : Sized where Option<Self> : Magic {}
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0568`.

src/test/ui/typeck/typeck-auto-trait-no-supertraits.stderr

@@ -6,3 +6,4 @@ LL | auto trait Magic: Copy {}
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0568`.