https://bugzilla.redhat.com/show_bug.cgi?id=2085377
--- Comment #12 from jschmidb@de.ibm.com --- Thanks for your comments via mail Dan!
Building the rpm with "rpmbuild -bs ..." solved the build problem. I was using "rpmbuild -ba ...". I'm attaching the new rpm.
Regarding '%files devel' versus '%files', looks like I have just swapped the two symlinks. I'm attaching the new spec file with exchanged symlinks.
And I added a '%files static' section with
%files static %{_libdir}/%{name}.a