Use so._closesocket instead of socket (compilation issues on non-Windows)

src/auth.c

@@ -714,7 +714,7 @@ int checkACL2(struct clientparam * param, int pre){
 						dup = *acentry;
 						res = handleredirect(param, &dup);
 						if(!res) break;
-						if(param->remsock != INVALID_SOCKET) closesocket(param->remsock);
+						if(param->remsock != INVALID_SOCKET) so._closesocket(param->remsock);
 						param->remsock = INVALID_SOCKET;
 					}
 					return res;