Adjust usage of std::io::ErrorKind to be core compatible

* Checking exhaustion will no longer be possible for `repr_bitpacked`. We can rely on `non_exhaustive_omitted_patterns` to maintain the exhaustive property for us instead.
* `ErrorKind::as_str` is private, but it's only usage is trivially replaced with `Display::fmt`
* The features io_error_inprogress, io_error_more, and io_error_uncategorized will all need to be enabled

Author: bushrat011899

library/std/src/io/error.rs

@@ -1038,7 +1038,7 @@ impl fmt::Display for Error {
                 write!(fmt, "{detail} (os error {code})")
             }
             ErrorData::Custom(ref c) => c.error.fmt(fmt),
-            ErrorData::Simple(kind) => write!(fmt, "{}", kind.as_str()),
+            ErrorData::Simple(kind) => kind.fmt(fmt),
             ErrorData::SimpleMessage(msg) => msg.message.fmt(fmt),
         }
     }

library/std/src/io/error/repr_bitpacked.rs

@@ -288,11 +288,14 @@ where
 // couldn't verify.
 #[inline]
 fn kind_from_prim(ek: u32) -> Option<ErrorKind> {
+    #[allow_internal_unstable(non_exhaustive_omitted_patterns_lint)]
     macro_rules! from_prim {
         ($prim:expr => $Enum:ident { $($Variant:ident),* $(,)? }) => {{
             // Force a compile error if the list gets out of date.
+            #[deny(non_exhaustive_omitted_patterns)]
             const _: fn(e: $Enum) = |e: $Enum| match e {
-                $($Enum::$Variant => ()),*
+                $($Enum::$Variant => (),)*
+                _ => (),
             };
             match $prim {
                 $(v if v == ($Enum::$Variant as _) => Some($Enum::$Variant),)*

library/std/src/lib.rs

@@ -343,6 +343,9 @@
 #![feature(hashmap_internals)]
 #![feature(hint_must_use)]
 #![feature(int_from_ascii)]
+#![feature(io_error_inprogress)]
+#![feature(io_error_more)]
+#![feature(io_error_uncategorized)]
 #![feature(ip)]
 #![feature(iter_advance_by)]
 #![feature(iter_next_chunk)]