add cstring include to fix linux build

Author: SLJLMacarit

zed-unity-livelink-mono/src/PracticalSocket.cpp

@@ -18,6 +18,7 @@
  */
 
 #include "PracticalSocket.h"
+#include <cstring>
 
 #ifdef WIN32
 #include <winsock.h>         // For socket(), connect(), send(), and recv()