This package appears to include a private copy of valgrind.h. In the latest relase of valgrind 3.10.0 a bug was fixed for ppc32 and support was added for aarch64 and ppc64le. Please either update the private copy of valgrind.h (memcheck.h, callgrind.h, etc) or (better) make your package BuildRequires: valgrind-devel and use the system installed headers.
Upstream patch: https://github.com/cockpit-project/cockpit/pull/1222
cockpit-0.25-1.fc21 has been submitted as an update for Fedora 21. https://admin.fedoraproject.org/updates/cockpit-0.25-1.fc21
Package cockpit-0.25-1.fc21: * should fix your issue, * was pushed to the Fedora 21 testing repository, * should be available at your local mirror within two days. Update it with: # su -c 'yum update --enablerepo=updates-testing cockpit-0.25-1.fc21' as soon as you are able to. Please go to the following url: https://admin.fedoraproject.org/updates/FEDORA-2014-11320/cockpit-0.25-1.fc21 then log in and leave karma (feedback).
cockpit-0.25-1.fc21 has been pushed to the Fedora 21 stable repository. If problems still persist, please make note of it in this bug report.