set RDP output enabled by default (stable 1.2)

This patch fixes a bug found by Marek Romanowic: the RDP peer output must
be enabled by default, or we have to unfocus/focus the RDP client window to
have disable/enable output messages sent (and finally receive updates).
diff --git a/src/compositor-rdp.c b/src/compositor-rdp.c
index 191d673..4d369cc 100644
--- a/src/compositor-rdp.c
+++ b/src/compositor-rdp.c
@@ -571,7 +571,7 @@
 rdp_peer_context_new(freerdp_peer* client, RdpPeerContext* context)
 {
 	context->item.peer = client;
-	context->item.flags = 0;
+	context->item.flags = RDP_PEER_OUTPUT_ENABLED;
 
 	context->rfx_context = rfx_context_new();
 	context->rfx_context->mode = RLGR3;