[compat-ffmpeg28/el7] (7 commits) ...Update to 2.8.18

Summary of changes: 787c10d... Rebuild for libdc1394 (*) 352c95c... Disable LTO (*) 124096e... update changelog (*) 445e390... Enable LTO for x86_64 (*) 5fd866e... - Rebuilt for https://fedoraproject.org/wiki/Fedora_34_Mass (*) 9c39e55... - Rebuilt for https://fedoraproject.org/wiki/Fedora_35_Mass (*) 94f3cbf... Update to 2.8.18 (*) (*) This commit already existed in another branch; no separate mail sent