Bump liberty, use iscntrl_ascii()

degesch.c

@@ -2246,7 +2246,7 @@ config_validate_nonjunk_string
 	{
 		// Not even a tabulator
 		unsigned char c = item->value.string.str[i];
-		if (c < 32)
+		if (iscntrl_ascii (c))
 		{
 			error_set (e, "control characters are not allowed");
 			return false;
@@ -8059,7 +8059,7 @@ static bool
 validate_server_name (const char *name)
 {
 	for (const unsigned char *p = (const unsigned char *) name; *p; p++)
-		if (*p < 32 || *p == '.')
+		if (iscntrl_ascii (*p) || *p == '.')
 			return false;
 	return true;
 }