compile fix for >=vdr-2.3.1 
suggested by MatthiasK on vdr-portal.de

Signed-off-by: Joerg Bornkessel <hd_brummy@gentoo.org> ( 25 Dec 2019 )
diff -Naur remoteosd-1.0.0.orig/menu.c remoteosd-1.0.0/menu.c
--- remoteosd-1.0.0.orig/menu.c	2019-12-25 21:59:10.907492713 +0100
+++ remoteosd-1.0.0/menu.c	2019-12-25 22:01:09.717492713 +0100
@@ -69,7 +69,8 @@
 	}
 
 	if (RemoteOsdSetup.tuneServer) {
-		cChannel *channel = Channels.GetByNumber(cDevice::CurrentChannel());
+		LOCK_CHANNELS_READ;
+		const cChannel *channel = Channels->GetByNumber(cDevice::CurrentChannel());
 		CmdCHAN(channel);
 	}
 
@@ -98,7 +99,7 @@
 	return cmd.responseCode;
 }
 
-bool cRemoteOsdMenu::CmdCHAN(cChannel *Channel) {
+bool cRemoteOsdMenu::CmdCHAN(const cChannel *Channel) {
 	SvdrpCommand_v1_0 cmd;
 	cmd.command = cString::sprintf("CHAN %s\r\n", *Channel->GetChannelID().ToString());
 	cmd.handle = svdrp.handle;
diff -Naur remoteosd-1.0.0.orig/menu.h remoteosd-1.0.0/menu.h
--- remoteosd-1.0.0.orig/menu.h	2019-12-25 21:59:10.906492713 +0100
+++ remoteosd-1.0.0/menu.h	2019-12-25 22:01:37.733492713 +0100
@@ -27,7 +27,7 @@
 		bool			isEmpty;
 		bool			plugOsd;
 
-		bool CmdCHAN(cChannel *Channel);
+		bool CmdCHAN(const cChannel *Channel);
 		bool CmdHITK(const char *Key);
 		bool CmdLSTO();
 		bool CmdOSDT();