Disable artifact deserialization in non x86-64 for now

tests/compilers/artifact.rs

@@ -21,6 +21,7 @@ fn artifact_serialization_roundtrip() {
 }
 
 #[test]
+#[cfg(target_arch = "x86_64")]
 fn artifact_deserialization_roundtrip() {
     // This test is included to make sure we don't break the serialized format
     // by mistake. Otherwise, everything in this test is already tested in