add sndio driver

backport commit 0b3496f:
Add support for SDL3 joystick input driver

Index: drivers/SCsub
--- drivers/SCsub.orig
+++ drivers/SCsub
@@ -17,6 +17,7 @@ SConscript("alsa/SCsub")
 if env["platform"] == "ios" or env["platform"] == "macos":
     SConscript("coreaudio/SCsub")
 SConscript("pulseaudio/SCsub")
+SConscript("sndio/SCsub")
 if env["platform"] == "windows":
     SConscript("wasapi/SCsub")
     if not env.msvc:
@@ -51,6 +52,11 @@ if env["metal"]:
         print_error("Target platform '{}' does not support the Metal rendering driver".format(env["platform"]))
         Exit(255)
     SConscript("metal/SCsub")
+
+# Input drivers
+if env["sdl"] and env["platform"] in ["linuxbsd", "macos", "windows"]:
+    # TODO: Evaluate support for Android, iOS, and Web.
+    SConscript("sdl/SCsub")
 
 # Core dependencies
 SConscript("png/SCsub")
