Remove feature gates for stabilized features

Author: saethlin

crates/core_arch/src/lib.rs

@@ -20,14 +20,12 @@
     tbm_target_feature,
     sse4a_target_feature,
     arm_target_feature,
-    aarch64_target_feature,
     cmpxchg16b_target_feature,
     avx512_target_feature,
     mips_target_feature,
     powerpc_target_feature,
     wasm_target_feature,
     abi_unadjusted,
-    adx_target_feature,
     rtm_target_feature,
     f16c_target_feature,
     allow_internal_unstable,