[new port] x11/libXpresent/: X11 Present library

[madpilot]

Summary

I created this patch while upgrading XFCE to 4.14.

The xfce4-wm port, containing xfce window manager, can link to this library using it as a backend for vsync.

I'd like to add it to the ports tree, so that, after the XFCE upgrade, I can enable support for it to the window manager.

I set x11 as port maintainer, is this acceptable?

Related xfce review: D21278

Test Plan

I have tested it in poudriere with tier 1 platforms, and tested with the xfce window manager from D21278 after adapting the port to use it.

[zeising]

x11/libXpresent/Makefile

16 ↗

(On Diff #61660)

Should be USES=xorg-cat:lib

[madpilot]

Fix USES.

[zeising]

Approved.
It makes sense to make the port owned by x11@
It doesn't need portmgr approval, Uses/xorg.mk is owned by x11@.