Your package fails to build with the newest autoconf-2.71, which was part of a recent wide Fedora change. More information about Fedora autoconf Change available here: https://fedoraproject.org/wiki/Changes/Autoconf_271#How_To_Test. The easiest way to reproduce the problem is to execute a fedora scratch-build on your package. Thank you for cooperation!
it's fixed in arts-1.5.10-50.fc36