Created attachment 206093 [details]
As with other lv2 ports, C++11 compiler needs to be used and -mtune=generic -msse -msse2 need to be removed.
A commit references this bug:
Date: Sat Jul 27 06:01:45 UTC 2019
New revision: 507381
audio/string-machine-lv2: Fix build on non-x86
Reported by: pkubaj
Committed the patch that solves the same problem in a different way.
Thank you for your report!