ci: install Xwayland .pc file

See https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/3621

.builds/alpine.yml

@@ -19,7 +19,7 @@ packages:
   - wayland-protocols
   - xcb-util-image-dev
   - xcb-util-wm-dev
-  - xwayland
+  - xwayland-dev
   - hwdata
 sources:
   - https://github.com/swaywm/sway

.builds/freebsd.yml

@@ -25,6 +25,7 @@ packages:
 - x11/libX11
 - x11/pixman
 - x11/xcb-util-wm
+- x11-servers/xwayland-devel
 - misc/hwdata
 sources:
 - https://github.com/swaywm/sway