[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