camera/pipewire: Implement the XDP Camera portal

[km9l]

Description

This helps the Pipewire camera driver to access cameras in a sandboxed environment without host Pipewire socket access. Unlike other platforms, no event is sent when the user rejects camera access. This is because there is no mechanism to query cameras through the portal, and we only obtain access to the Pipewire fd if the user accepts the request. The Pipewire driver will attempt to open the host socket instead.

Maybe allowing a SDL_GetCameraPermissionState call happen before SDL_GetCameras could work? I didn't bother doing any API change for now.

[sezero]

Don't know about the rest, but can you add the following so that it still compiles against older headers, please?

diff --git a/src/core/linux/SDL_dbus.h b/src/core/linux/SDL_dbus.h
--- a/src/core/linux/SDL_dbus.h
+++ b/src/core/linux/SDL_dbus.h
@@ -34,6 +34,9 @@
 #ifndef DBUS_TIMEOUT_INFINITE
 #define DBUS_TIMEOUT_INFINITE ((int) 0x7fffffff)
 #endif
+#ifndef DBUS_TYPE_UNIX_FD
+#define DBUS_TYPE_UNIX_FD ((int) 'h')
+#endif
 
 typedef struct SDL_DBusContext
 {

[km9l]

Don't know about the rest, but can you add the following so that it still compiles against older headers, please?

Odd, that definition was a recent thing? I'll add it, thanks for pointing it out.