obs-studio: add wayland to buildInputs

obs-studio (git master) has native wayland support.
To build further releases of obs-studio this adds wayland to buildInputs

https://github.com/obsproject/obs-studio/wiki/Install-Instructions#linux-build-directions
https://github.com/obsproject/obs-studio/pull/2484

pkgs/applications/video/obs-studio/default.nix

@@ -17,6 +17,7 @@
 , libv4l
 , x264
 , curl
+, wayland
 , xorg
 , makeWrapper
 , pkg-config
@@ -67,6 +68,7 @@ in mkDerivation rec {
     qtx11extras
     qtsvg
     speex
+    wayland
     x264
     libvlc
     makeWrapper