std: Require &mut self for Iterator::all

Keeps the method consistent with `Iterator::any`.

Closes #22617
[breaking-change]

src/libcore/iter.rs

@@ -637,8 +637,8 @@ pub trait IteratorExt: Iterator + Sized {
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    fn all<F>(self, mut f: F) -> bool where F: FnMut(Self::Item) -> bool {
-        for x in self { if !f(x) { return false; } }
+    fn all<F>(&mut self, mut f: F) -> bool where F: FnMut(Self::Item) -> bool {
+        for x in self.by_ref() { if !f(x) { return false; } }
         true
     }
 

src/librustc/middle/ty.rs

@@ -3883,7 +3883,7 @@ pub fn is_type_representable<'tcx>(cx: &ctxt<'tcx>, sp: Span, ty: Ty<'tcx>)
                 let types_a = substs_a.types.get_slice(subst::TypeSpace);
                 let types_b = substs_b.types.get_slice(subst::TypeSpace);
 
-                let pairs = types_a.iter().zip(types_b.iter());
+                let mut pairs = types_a.iter().zip(types_b.iter());
 
                 pairs.all(|(&a, &b)| same_type(a, b))
             }