Codechange: move SLF_NO_NETWORK_SYNC into settings

It is a settings-only flag, so don't pollute SaveLoad code with it.

src/saveload/saveload.h

@@ -896,6 +896,7 @@ void WriteValue(void *ptr, VarType conv, int64 val);
 void SlSetArrayIndex(uint index);
 int SlIterateArray();
 
+uint SlCalcConvMemLen(VarType conv);
 void SlAutolength(AutolengthProc *proc, void *arg);
 size_t SlGetFieldLength();
 void SlSetLength(size_t length);