Rollup merge of #132734 - RalfJung:platform-intrinsic, r=compiler-errors

remove 'platform-intrinsic' ABI leftovers

This was removed a while ago, but some parts haven't been fully cleaned up.

compiler/rustc_hir_analysis/src/check/intrinsic.rs

@@ -1,5 +1,4 @@
-//! Type-checking for the rust-intrinsic and platform-intrinsic
-//! intrinsics that the compiler exposes.
+//! Type-checking for the rust-intrinsic intrinsics that the compiler exposes.
 
 use rustc_abi::ExternAbi;
 use rustc_errors::codes::*;