py: cam.py: Fix multi camera capture without -C

-C flag is supposed to affect only the camera that was previously
defined in the arguments. That's not the case, and, e.g.:

cam.py -c2 -C -c3

causes camera 3 to start capturing, but it stops after the initial
Requests have been completed.

Fix the issue by filtering out camera contexts that do not have -C
defined.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/py/cam/cam.py

@@ -434,7 +434,10 @@ def main():
         if args.info:
             ctx.do_cmd_info()
 
-    if args.capture:
+    # Filter out capture contexts which are not marked for capture
+    contexts = [ctx for ctx in contexts if ctx.opt_capture > 0]
+
+    if contexts:
         state = CaptureState(cm, contexts)
 
         if args.renderer == 'null':