add aarch64 as base microarch in ARM family

LbPlatformUtils/_arch_details/_arm.py

@@ -18,7 +18,13 @@ def defs():
 
     # Data based on the information found at
     # https://javathunderx.blogspot.com/2018/11/cheat-sheet-for-cpuinfo-features-on.html
-    data = [("armv8_a", ["fp", "asimd", "evtstrm", "aes", "pmull", "sha1", "sha2"])]
+    data = [("aarch64", [])]
+    data.append(
+        (
+            "armv8_a",
+            data[-1][1] + ["fp", "asimd", "evtstrm", "aes", "pmull", "sha1", "sha2"],
+        )
+    )
     data.append(("armv8.1_a", data[-1][1] + ["crc32", "atomics", "asimdrdm"]))
     data.append(("armv8.2_a", data[-1][1] + ["dcpop"]))
     data.append(("armv8.3_a", data[-1][1] + ["jscvt", "lrcpc"]))