Allow unused macro rules for two macros

The unused macro rules lint is an upcoming lint
added to the rust compiler. This commit prepares
for the introduction so that the CI passes.

Author: est31

crates/core_arch/src/macros.rs

@@ -93,7 +93,7 @@ macro_rules! types {
     )*)
 }
 
-#[allow(unused_macros)]
+#[allow(unused)]
 macro_rules! simd_shuffle2 {
     ($x:expr, $y:expr, <$(const $imm:ident : $ty:ty),+ $(,)?> $idx:expr $(,)?) => {{
         struct ConstParam<$(const $imm: $ty),+>;

crates/core_arch/src/powerpc/altivec.rs

@@ -356,6 +356,7 @@ mod sealed {
 
     }
 
+    #[allow(unknown_lints, unused_macro_rules)]
     macro_rules! impl_vec_trait {
         ([$Trait:ident $m:ident] $fun:ident ($a:ty)) => {
             impl $Trait for $a {