updated cmakerules to autodetect if gettext can be used

fixed error if gettext is disabled

src/main.cpp

@@ -1132,10 +1132,12 @@ int main(int argc, char *argv[])
 	// Create user data directory
 	fs::CreateDir(porting::path_userdata);
 
+#ifdef LC_MESSAGES
 	setlocale(LC_MESSAGES, "");
 	bindtextdomain("minetest", (porting::path_userdata+"/locale").c_str());
 	textdomain("minetest");
-	
+#endif
+
 	// Initialize debug streams
 #ifdef RUN_IN_PLACE
 	std::string debugfile = DEBUGFILE;