Update stdsimd to undo an accidental stabilization

Closes #52403

Author: alexcrichton

src/libcore/lib.rs

@@ -244,9 +244,6 @@ macro_rules! vector_impl { ($([$f:ident, $($args:tt)*]),*) => { $($f!($($args)*)
 #[cfg(not(stage0))] // allow changes to how stdsimd works in stage0
 mod coresimd;
 
-#[unstable(feature = "stdsimd", issue = "48556")]
-#[cfg(not(stage0))]
-pub use coresimd::simd;
 #[stable(feature = "simd_arch", since = "1.27.0")]
 #[cfg(not(stage0))]
 pub use coresimd::arch;

src/libstd/lib.rs

@@ -532,12 +532,8 @@ mod stdsimd;
 #[cfg(not(stage0))]
 mod coresimd {
     pub use core::arch;
-    pub use core::simd;
 }
 
-#[unstable(feature = "stdsimd", issue = "48556")]
-#[cfg(all(not(stage0), not(test)))]
-pub use stdsimd::simd;
 #[stable(feature = "simd_arch", since = "1.27.0")]
 #[cfg(all(not(stage0), not(test)))]
 pub use stdsimd::arch;

src/stdsimd

@@ -15,6 +15,5 @@ const EXPECTED = {
         { 'path': 'std', 'name': 'str' },
         { 'path': 'std', 'name': 'u8' },
         { 'path': 'std::ffi', 'name': 'CStr' },
-        { 'path': 'std::simd', 'name': 'u8x2' },
     ],
 };