Auto merge of #43710 - zackmdavis:field_init_shorthand_power_slam, r=Mark-Simulacrum

use field init shorthand EVERYWHERE

Like #43008 (f668999), but [(lacking reasons to be more timid)](https://github.com/rust-lang/rust/pull/43008#issuecomment-312463564) _much more aggressive_.

r? @Mark-Simulacrum

src/liballoc/vec.rs

@@ -1728,9 +1728,9 @@ impl<T> IntoIterator for Vec<T> {
             mem::forget(self);
             IntoIter {
                 buf: Shared::new_unchecked(begin),
-                cap: cap,
+                cap,
                 ptr: begin,
-                end: end,
+                end,
             }
         }
     }