more robust support for ARM64 platform;

--- a/ANNOUNCE	Tue Aug 08 23:51:01 2023 +0200
+++ b/ANNOUNCE	Tue Aug 08 23:55:33 2023 +0200
@@ -16,6 +16,8 @@
 
 * HOL: updates and improvements of Sledgehammer.
 
+* ML: more robust support for ARM64 platform (native Apple Silicon).
+
 * ML: heap usage and stored heap size has been significantly reduced.
 
 * ML: improved implementations of functor Table() and corresponding Set().