[platforms/x11/standalone] Remove SGI swap control and video sync

Summary:
Current hardware should suppport either GLX_EXT_swap_control or
GLX_MESA_swap_control. To simplify code remove the usage of SGI extensions.

Test Plan: kwin_x11 tested on i915.

Reviewers: #kwin, zzag

Reviewed By: #kwin, zzag

Subscribers: davidedmundson, kwin

Tags: #kwin

Maniphest Tasks: T11071

Differential Revision: https://phabricator.kde.org/D23510