After step #8 (rpmbuild -ba /root/rpmbuild/SPECS/ImageMagick.spec) I get the following output:
RPM build errors:
File not found by glob: /root/rpmbuild/BUILDROOT/ImageMagick-6.9.10.68-3.el7.x86_64/usr/lib64/libMagick++-6*.so*
As a result, there's no rpm in the /root/rpmbuild/RPMS directory...