vcmi can be compiled as single app on Linux

TODO: check compilation on Win/Mac using Github Actions

client/CServerHandler.cpp

@@ -25,12 +25,15 @@
 #include "../lib/CAndroidVMHelper.h"
 #elif defined(VCMI_IOS)
 #include "ios/utils.h"
-#include "../server/CVCMIServer.h"
-
 #include <dispatch/dispatch.h>
 #else
 #include "../lib/Interprocess.h"
 #endif
+
+#ifdef SINGLE_PROCESS_APP
+#include "../server/CVCMIServer.h"
+#endif
+
 #include "../lib/CConfigHandler.h"
 #include "../lib/CGeneralTextHandler.h"
 #include "../lib/CThreadHelper.h"
@@ -142,7 +145,7 @@ void CServerHandler::resetStateForLobby(const StartInfo::EMode mode, const std::
 	else
 		myNames.push_back(settings["general"]["playerName"].String());
 
-#if !defined(VCMI_ANDROID) && !defined(VCMI_IOS)
+#if !defined(VCMI_ANDROID) && !defined(SINGLE_PROCESS_APP)
 	shm.reset();
 
 	if(!settings["session"]["disable-shm"].Bool())