Source package webkitgtk-2.2.4-1 used by EPEL7 does not support ppc64le. A newer version supporting this architecture should be used instead.
If I remeber things correctly that support for ppc64le landed in 2.4.x and I don't think we will rebase to that version. The support for ppc64le is the matter of backporting this patch https://bugs.webkit.org/show_bug.cgi?id=135647 to 2.2.x sources.
aarch64 is similarly affected. RHEL 7.2 rebased webkitgtk3 to 2.4.9, so I think it would be appropriate for webkitgtk to do the same. Furthermore, due to geoclue2's (IMHO erroneous) obsoletes of geoclue (bug 1221940 and bug 1285479), webkitgtk really needs to be updated in order to use the former.
webkitgtk-2.4.9-1.el7 has been submitted as an update to Fedora EPEL 7. https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2015-e8a59bbd07
webkitgtk-2.4.9-1.el7 has been pushed to the Fedora EPEL 7 testing repository. If problems still persist, please make note of it in this bug report. If you want to test the update, you can install it with $ su -c 'yum --enablerepo=epel-testing update webkitgtk' You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2015-e8a59bbd07
webkitgtk-2.4.9-1.el7 has been pushed to the Fedora EPEL 7 stable repository. If problems still persist, please make note of it in this bug report.