fix build constraints

pkg/atomicbitops/aligned_64bit.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build !arm,!386
+// +build amd64 arm64
 
 package atomicbitops
 

tools/bazeldefs/tags.bzl

@@ -33,6 +33,10 @@ archs = [
     "_s390x",
     "_sparc64",
     "_x86",
+
+    # Pseudo-architectures to group by word side.
+    "_32bit",
+    "_64bit",
 ]
 
 oses = [