SDL: Added support for multiple seats with touch input on Wayland

SDL Commits
1 
From 03c19efbd17f72f70ee021de6d2549eb0be3bb56 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Sat, 24 Jul 2021 15:25:50 -0700
Subject: [PATCH] Added support for multiple seats with touch input on Wayland

This fixes bug https://github.com/libsdl-org/SDL/issues/4517
---
 src/video/wayland/SDL_waylandevents.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/video/wayland/SDL_waylandevents.c b/src/video/wayland/SDL_waylandevents.c
index d70c31cdb..b69171ab6 100644
--- a/src/video/wayland/SDL_waylandevents.c
+++ b/src/video/wayland/SDL_waylandevents.c
@@ -941,13 +941,13 @@ seat_handle_capabilities(void *data, struct wl_seat *seat,
     }
 
     if ((caps & WL_SEAT_CAPABILITY_TOUCH) && !input->touch) {
-        SDL_AddTouch(1, SDL_TOUCH_DEVICE_DIRECT, "wayland_touch");
+        SDL_AddTouch((SDL_TouchID)seat, SDL_TOUCH_DEVICE_DIRECT, "wayland_touch");
         input->touch = wl_seat_get_touch(seat);
         wl_touch_set_user_data(input->touch, input);
         wl_touch_add_listener(input->touch, &touch_listener,
                                  input);
     } else if (!(caps & WL_SEAT_CAPABILITY_TOUCH) && input->touch) {
-        SDL_DelTouch(1);
+        SDL_DelTouch((SDL_TouchID)seat);
         wl_touch_destroy(input->touch);
         input->touch = NULL;
     }