Tweak wording of E0275 WF errors

Modify the main error message to read better:

```
error[E0275]: overflow evaluating whether `&'a mut Bar` is well-formed
```

Author: estebank

compiler/rustc_trait_selection/src/error_reporting/traits/overflow.rs

@@ -99,6 +99,15 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                             "overflow assigning `{a}` to `{b}`",
                         )
                     }
+                    ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(term)) => {
+                        let term = with_short_path(self.tcx, term);
+                        struct_span_code_err!(
+                            self.dcx(),
+                            span,
+                            E0275,
+                            "overflow evaluating whether `{term}` is well-formed",
+                        )
+                    }
                     _ => {
                         let pred_str = with_short_path(self.tcx, predicate);
                         struct_span_code_err!(

tests/ui/associated-types/issue-64855-2.rs

@@ -3,6 +3,6 @@
 // also inadvertently a test for the (non-)co-inductiveness of WF predicates.
 
 pub struct Bar<'a>(&'a Self) where Self: ;
-//~^ ERROR overflow evaluating the requirement `Bar<'a> well-formed`
+//~^ ERROR overflow evaluating whether `Bar<'a>` is well-formed
 
 fn main() {}

tests/ui/associated-types/issue-64855-2.stderr

@@ -1,4 +1,4 @@
-error[E0275]: overflow evaluating the requirement `Bar<'a> well-formed`
+error[E0275]: overflow evaluating whether `Bar<'a>` is well-formed
   --> $DIR/issue-64855-2.rs:5:36
    |
 LL | pub struct Bar<'a>(&'a Self) where Self: ;

tests/ui/associated-types/issue-64855.rs

@@ -8,6 +8,6 @@ pub trait Foo {
 
 pub struct Bar<T>(<Self as Foo>::Type) where Self: ;
 //~^ ERROR the trait bound `Bar<T>: Foo` is not satisfied
-//~| ERROR overflow evaluating the requirement `Bar<T> well-formed`
+//~| ERROR overflow evaluating whether `Bar<T>` is well-formed
 
 fn main() {}

tests/ui/associated-types/issue-64855.stderr

@@ -15,7 +15,7 @@ help: this trait has no implementations, consider adding one
 LL | pub trait Foo {
    | ^^^^^^^^^^^^^
 
-error[E0275]: overflow evaluating the requirement `Bar<T> well-formed`
+error[E0275]: overflow evaluating whether `Bar<T>` is well-formed
   --> $DIR/issue-64855.rs:9:46
    |
 LL | pub struct Bar<T>(<Self as Foo>::Type) where Self: ;

tests/ui/const-generics/generic_const_exprs/adt_wf_hang.rs

@@ -9,6 +9,6 @@ struct U;
 struct S<const N: U>()
 where
     S<{ U }>:;
-//~^ ERROR: overflow evaluating the requirement `S<{ U }> well-formed`
+//~^ ERROR: overflow evaluating whether `S<{ U }>` is well-formed
 
 fn main() {}

tests/ui/const-generics/generic_const_exprs/adt_wf_hang.stderr

@@ -1,4 +1,4 @@
-error[E0275]: overflow evaluating the requirement `S<{ U }> well-formed`
+error[E0275]: overflow evaluating whether `S<{ U }>` is well-formed
   --> $DIR/adt_wf_hang.rs:11:5
    |
 LL |     S<{ U }>:;

tests/ui/const-generics/mgca/const-ctor-overflow-eval.rs

@@ -6,14 +6,14 @@ use std::marker::ConstParamTy;
 struct U;
 
 #[derive(ConstParamTy, PartialEq, Eq)]
-//~^ ERROR overflow evaluating the requirement `S<U> well-formed`
-//~| ERROR overflow evaluating the requirement `S<U> well-formed`
+//~^ ERROR overflow evaluating whether `S<U>` is well-formed
+//~| ERROR overflow evaluating whether `S<U>` is well-formed
 
 struct S<const N: U>()
 where
     S<{ U }>:;
-//~^ ERROR overflow evaluating the requirement `S<U> well-formed`
-//~| ERROR overflow evaluating the requirement `S<U> well-formed`
-//~| ERROR overflow evaluating the requirement `S<U> well-formed`
+//~^ ERROR overflow evaluating whether `S<U>` is well-formed
+//~| ERROR overflow evaluating whether `S<U>` is well-formed
+//~| ERROR overflow evaluating whether `S<U>` is well-formed
 
 fn main() {}

tests/ui/const-generics/mgca/const-ctor-overflow-eval.stderr

@@ -1,4 +1,4 @@
-error[E0275]: overflow evaluating the requirement `S<U> well-formed`
+error[E0275]: overflow evaluating whether `S<U>` is well-formed
   --> $DIR/const-ctor-overflow-eval.rs:14:5
    |
 LL |     S<{ U }>:;
@@ -13,7 +13,7 @@ LL | where
 LL |     S<{ U }>:;
    |     ^^^^^^^^ required by this bound in `S`
 
-error[E0275]: overflow evaluating the requirement `S<U> well-formed`
+error[E0275]: overflow evaluating whether `S<U>` is well-formed
   --> $DIR/const-ctor-overflow-eval.rs:14:5
    |
 LL |     S<{ U }>:;
@@ -29,7 +29,7 @@ LL |     S<{ U }>:;
    |     ^^^^^^^^ required by this bound in `S`
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
-error[E0275]: overflow evaluating the requirement `S<U> well-formed`
+error[E0275]: overflow evaluating whether `S<U>` is well-formed
   --> $DIR/const-ctor-overflow-eval.rs:14:5
    |
 LL |     S<{ U }>:;
@@ -45,7 +45,7 @@ LL |     S<{ U }>:;
    |     ^^^^^^^^ required by this bound in `S`
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
-error[E0275]: overflow evaluating the requirement `S<U> well-formed`
+error[E0275]: overflow evaluating whether `S<U>` is well-formed
   --> $DIR/const-ctor-overflow-eval.rs:8:24
    |
 LL | #[derive(ConstParamTy, PartialEq, Eq)]
@@ -60,7 +60,7 @@ LL | where
 LL |     S<{ U }>:;
    |     ^^^^^^^^ required by this bound in `S`
 
-error[E0275]: overflow evaluating the requirement `S<U> well-formed`
+error[E0275]: overflow evaluating whether `S<U>` is well-formed
   --> $DIR/const-ctor-overflow-eval.rs:8:35
    |
 LL | #[derive(ConstParamTy, PartialEq, Eq)]

tests/ui/higher-ranked/trait-bounds/issue-95230.rs

@@ -5,6 +5,6 @@
 pub struct Bar
 where
     for<'a> &'a mut Self:;
-//~^ ERROR overflow evaluating the requirement `for<'a> &'a mut Bar well-formed`
+//~^ ERROR: overflow evaluating whether `&'a mut Bar` is well-formed
 
 fn main() {}