river: re-add wl_drm support for now

It seems to be a bit too early to drop support for this legacy protocol.

Xwayland apparently still relies on it for hardware acceleration as do
fairly recent mesa versions still in widespread use.

deps/zig-wlroots

@@ -1 +1 @@
-Subproject commit 68ce60769c6a8019c43de35197f4596eaac4df48
+Subproject commit aae7f237e270ed8fc2ff10f3a661ced618c527cf

river/Server.zig

@@ -102,6 +102,12 @@ pub fn init(self: *Self) !void {
     try self.renderer.initWlShm(self.wl_server);
 
     if (self.renderer.getDmabufFormats() != null and self.renderer.getDrmFd() >= 0) {
+        // wl_drm is a legacy interface and all clients should switch to linux_dmabuf.
+        // However, enough widely used clients still rely on wl_drm that the pragmatic option
+        // is to keep it around for the near future.
+        // TODO remove wl_drm support
+        _ = try wlr.Drm.create(self.wl_server, self.renderer);
+
         self.linux_dmabuf = try wlr.LinuxDmabufV1.createWithRenderer(self.wl_server, 4, self.renderer);
     }