remove platform-intrinsics ABI; make SIMD intrinsics be regular intrinsics

compiler/rustc_error_codes/src/error_codes/E0511.md

@@ -3,9 +3,9 @@ Invalid monomorphization of an intrinsic function was used.
 Erroneous code example:
 
 ```compile_fail,E0511
-#![feature(platform_intrinsics)]
+#![feature(intrinsics)]
 
-extern "platform-intrinsic" {
+extern "rust-intrinsic" {
     fn simd_add<T>(a: T, b: T) -> T;
 }
 
@@ -19,13 +19,13 @@ The generic type has to be a SIMD type. Example:
 
 ```
 #![feature(repr_simd)]
-#![feature(platform_intrinsics)]
+#![feature(intrinsics)]
 
 #[repr(simd)]
 #[derive(Copy, Clone)]
 struct i32x2(i32, i32);
 
-extern "platform-intrinsic" {
+extern "rust-intrinsic" {
     fn simd_add<T>(a: T, b: T) -> T;
 }