What significance this has - beside the fail - I don’t know - but it is related to the configuration of the makefile maybe even the source code.
Consult AUR maintainer first - then upstream.
Supported versions do not include Arch based Linux
https://support.sophos.com/support/s/article/KB-000033389?language=en_US
- Supported distributions (latest minor point or LTS version):
- Amazon Linux, Amazon Linux 2
- CentOS 6/7/8
- Debian 9, 10
- Oracle Linux 6/7/8
- Red Hat Enterprise Linux 6/7/8
- SUSE 12/15
- Ubuntu 16/18 LTS