Rollup merge of #128495 - joboet:more_memcmp, r=scottmcm

core: use `compare_bytes` for more slice element types

`bool`, `NonZero<u8>`, `Option<NonZero<u8>>` and `ascii::Char` can be compared the same way as `u8`.

Author: matthiaskrgr

tests/fail/uninit/uninit_alloc_diagnostic.stderr

@@ -1,8 +1,8 @@
 error: Undefined Behavior: reading memory at ALLOC[0x0..0x10], but memory is uninitialized at [0x4..0x10], and this operation requires initialized memory
   --> RUSTLIB/core/src/slice/cmp.rs:LL:CC
    |
-LL |         let mut order = unsafe { compare_bytes(left.as_ptr(), right.as_ptr(), len) as isize };
-   |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ reading memory at ALLOC[0x0..0x10], but memory is uninitialized at [0x4..0x10], and this operation requires initialized memory
+LL |         let mut order = unsafe { compare_bytes(left, right, len) as isize };
+   |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ reading memory at ALLOC[0x0..0x10], but memory is uninitialized at [0x4..0x10], and this operation requires initialized memory
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail/uninit/uninit_alloc_diagnostic_with_provenance.stderr

@@ -1,8 +1,8 @@
 error: Undefined Behavior: reading memory at ALLOC[0x0..0x8], but memory is uninitialized at [0x4..0x8], and this operation requires initialized memory
   --> RUSTLIB/core/src/slice/cmp.rs:LL:CC
    |
-LL |         let mut order = unsafe { compare_bytes(left.as_ptr(), right.as_ptr(), len) as isize };
-   |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ reading memory at ALLOC[0x0..0x8], but memory is uninitialized at [0x4..0x8], and this operation requires initialized memory
+LL |         let mut order = unsafe { compare_bytes(left, right, len) as isize };
+   |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ reading memory at ALLOC[0x0..0x8], but memory is uninitialized at [0x4..0x8], and this operation requires initialized memory
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information