Implement the instruction_set attribute

compiler/rustc_span/src/symbol.rs

@@ -212,6 +212,7 @@ symbols! {
         _d,
         _e,
         _task_context,
+        a32,
         aarch64_target_feature,
         abi,
         abi_amdgpu_kernel,
@@ -256,6 +257,7 @@ symbols! {
         arbitrary_enum_discriminant,
         arbitrary_self_types,
         arith_offset,
+        arm,
         arm_target_feature,
         array,
         arrays,
@@ -592,11 +594,13 @@ symbols! {
         inlateout,
         inline,
         inout,
+        instruction_set,
         intel,
         into_iter,
         into_result,
         intrinsics,
         irrefutable_let_patterns,
+        isa_attribute,
         isize,
         issue,
         issue_5723_bootstrap,
@@ -1065,6 +1069,7 @@ symbols! {
         sym,
         sync,
         sync_trait,
+        t32,
         target_arch,
         target_endian,
         target_env,