Fix unused const on aarch64

Author: kornelski

src/simd/mod.rs

@@ -68,8 +68,15 @@ pub const AVX_2: usize = 2;
     ),
 ))]
 pub const AVX_2_AND_SSE_42: usize = 3;
-#[cfg(httparse_simd)]
-const NONE: usize = usize::MAX;
+
+#[cfg(all(
+    httparse_simd,
+    any(
+        target_arch = "x86",
+        target_arch = "x86_64",
+    ),
+))]
+const NONE: usize = std::usize::MAX;
 #[cfg(all(
     httparse_simd,
     not(any(