lib/codegen-meta moved into lib/codegen. (#423)

* lib/codegen-meta moved into lib/codegen.

* Renamed codegen-meta and existing meta.

lib/codegen/meta-python/isa/arm64/__init__.py

@@ -0,0 +1,14 @@
+"""
+ARM 64-bit Architecture
+-----------------------
+
+ARMv8 CPUs running the Aarch64 architecture.
+"""
+
+from __future__ import absolute_import
+from . import defs
+from . import settings, registers  # noqa
+from cdsl.isa import TargetISA  # noqa
+
+# Re-export the primary target ISA definition.
+ISA = defs.ISA.finish()  # type: TargetISA