docs: do not inline x86 instrinsics into x86-64

This reduces the size of the `core/arch` HTML from about
187M to 132M.

crates/core_arch/src/mod.rs

@@ -23,7 +23,7 @@ pub mod arch {
     ///
     /// See the [module documentation](../index.html) for more details.
     #[cfg(any(target_arch = "x86", doc))]
-    #[doc(cfg(target_arch = "x86"))]
+    #[doc(cfg(any(target_arch = "x86", target_arch = "x86_64")))]
     #[stable(feature = "simd_x86", since = "1.27.0")]
     pub mod x86 {
         #[stable(feature = "simd_x86", since = "1.27.0")]
@@ -32,12 +32,18 @@ pub mod arch {
 
     /// Platform-specific intrinsics for the `x86_64` platform.
     ///
-    /// See the [module documentation](../index.html) for more details.
+    /// See the [module documentation](../index.html) for more details
+    /// and the [`x86`] module for common instrinsics.
     #[cfg(any(target_arch = "x86_64", doc))]
     #[doc(cfg(target_arch = "x86_64"))]
     #[stable(feature = "simd_x86", since = "1.27.0")]
     pub mod x86_64 {
         #[stable(feature = "simd_x86", since = "1.27.0")]
+        #[doc(no_inline)]
+        #[cfg(doc)]
+        pub use super::x86::*;
+        #[stable(feature = "simd_x86", since = "1.27.0")]
+        #[cfg(not(doc))]
         pub use crate::core_arch::x86::*;
         #[stable(feature = "simd_x86", since = "1.27.0")]
         pub use crate::core_arch::x86_64::*;