Comment # 2 on bug 1204697 from Egbert Eich

Ok, static libraries require the -ffat-lto-objects on the compiler command line
when doing LTO builds.

Easiest solution: expand the _lto_cflags definition:

%if "%{?_lto_cflags}" != ""
%global _lto_cflags %{_lto_cflags} -ffat-lto-objects
%endif

If we'd shipped the object directly in the RPM this problem would have occurred
immediately as the object would have been subject to stripping during install
post-processing. In this case, the objects would not have destroyed
reproducibility. 
Since this would have caused all sorts of warnings, the entire test suite was
wrapped in a tar ball which we extract when installing the package.