This also fixes the x25519_NEON symbol error when importing the gRPC
Python modules on ARM.

Change-Id: Id98cf6b0f9a3a8f5b88204bd0a6ad2346182ba3d

distributions since we don't use them and it's not sensible
to add them

application handle the authentication.

This opens the door for other serializers (such as e.g. FlatBuffers)
to share this code generator when using GRPC.

This reverts commit 5b304753.