Created attachment 204015 [details] patch Adding -stdlib=libstdc++ breaks this port - the problem is that GCC doesn't understand -stdlib.
Committed, thanks!
A commit references this bug: Author: yuri Date: Thu Apr 25 17:07:33 UTC 2019 New revision: 500037 URL: https://svnweb.freebsd.org/changeset/ports/500037 Log: audio/caps-lv2: fix build with GCC-based architectures PR: 237565 Submitted by: pkubaj Changes: head/audio/caps-lv2/Makefile