libobs: Add profiler section for send_packet

This makes it a bit more clear when muxing takes longer than expected
instead of attributing the time to the do_encode.

libobs/obs-encoder.c

@@ -882,15 +882,18 @@ static void send_first_video_packet(struct obs_encoder *encoder,
 	da_free(data);
 }
 
+static const char *send_packet_name = "send_packet";
 static inline void send_packet(struct obs_encoder *encoder,
 			       struct encoder_callback *cb,
 			       struct encoder_packet *packet)
 {
+	profile_start(send_packet_name);
 	/* include SEI in first video packet */
 	if (encoder->info.type == OBS_ENCODER_VIDEO && !cb->sent_first_packet)
 		send_first_video_packet(encoder, cb, packet);
 	else
 		cb->new_packet(cb->param, packet);
+	profile_end(send_packet_name);
 }
 
 void full_stop(struct obs_encoder *encoder)