Simplify static_assert_sizes.

We want to run them on all 64-bit platforms.

compiler/rustc_parse/src/parser/attr_wrapper.rs

@@ -454,7 +454,7 @@ fn make_token_stream(
 }
 
 // Some types are used a lot. Make sure they don't unintentionally get bigger.
-#[cfg(all(any(target_arch = "x86_64", target_arch = "aarch64"), target_pointer_width = "64"))]
+#[cfg(target_pointer_width = "64")]
 mod size_asserts {
     use super::*;
     use rustc_data_structures::static_assert_size;