(#3767) Some protection from malicious qvms - patches and ideas by Amanieu d'Antras and Ben Millwood

code/qcommon/q_shared.h

@@ -815,6 +815,7 @@ default values.
 
 #define CVAR_SERVER_CREATED	0x0800	// cvar was created by a server the client connected to.
 #define CVAR_VM_CREATED		0x1000	// cvar was created exclusively in one of the VMs.
+#define CVAR_PROTECTED		0x2000	// prevent modifying this var from VMs or the server
 #define CVAR_NONEXISTENT	0xFFFFFFFF	// Cvar doesn't exist.
 
 // nothing outside the Cvar_*() functions should modify these fields!