improve error reporting, remove duplicate code

include/Common.h

@@ -5,12 +5,15 @@ extern TSentry Sentry;
 
 #include <array>
 #include <atomic>
+#include <cstring>
 #include <deque>
 #include <functional>
 #include <memory>
 #include <mutex>
 #include <sstream>
 
+#include "Compat.h"
+
 #include "TConsole.h"
 
 struct Version {
@@ -158,4 +161,6 @@ void LogChatMessage(const std::string& name, int id, const std::string& msg);
 
 #define Biggest 30000
 std::string Comp(std::string Data);
-std::string DeComp(std::string Compressed);
+std::string DeComp(std::string Compressed);
+
+std::string GetPlatformAgnosticErrorString();

include/Compat.h

@@ -7,6 +7,7 @@
 #include <sys/socket.h>
 #include <termios.h>
 #include <unistd.h>
+#include <errno.h>
 using SOCKET = int;
 using DWORD = unsigned long;
 using PDWORD = unsigned long*;