Don't format tests/run-make/*/rmake.rs.

It's reasonable to want to, but in the current implementation this
causes multiple problems.

- All the `rmake.rs` files are formatted every time even when they
  haven't changed. This is because they get whitelisted unconditionally
  in the `OverrideBuilder`, before the changed files get added.

- The way `OverrideBuilder` works, if any files gets whitelisted then no
  unmentioned files will get traversed. This is surprising, and means
  that the `rmake.rs` entries broke the use of explicit paths to `x
  fmt`, and also broke `GITHUB_ACTIONS=true git check --fmt`.

The commit removes the `rmake.rs` entries, fixes the formatting of a
couple of files that were misformatted (not previously caught due to the
`GITHUB_ACTIONS` breakage), and bans `!`-prefixed entries in
`rustfmt.toml` because they cause all these problems.

Author: nnethercote

core/src/ptr/metadata.rs

@@ -209,18 +209,14 @@ impl<Dyn: ?Sized> DynMetadata<Dyn> {
         // Consider a reference like `&(i32, dyn Send)`: the vtable will only store the size of the
         // `Send` part!
         // SAFETY: DynMetadata always contains a valid vtable pointer
-        return unsafe {
-            crate::intrinsics::vtable_size(self.vtable_ptr() as *const ())
-        };
+        return unsafe { crate::intrinsics::vtable_size(self.vtable_ptr() as *const ()) };
     }
 
     /// Returns the alignment of the type associated with this vtable.
     #[inline]
     pub fn align_of(self) -> usize {
         // SAFETY: DynMetadata always contains a valid vtable pointer
-        return unsafe {
-            crate::intrinsics::vtable_align(self.vtable_ptr() as *const ())
-        };
+        return unsafe { crate::intrinsics::vtable_align(self.vtable_ptr() as *const ()) };
     }
 
     /// Returns the size and alignment together as a `Layout`