clarified arm64-linux base line: prefer Pi OS, which is based on slightly older Debian;

--- a/Admin/PLATFORMS	Sat Oct 03 19:56:02 2020 +0200
+++ b/Admin/PLATFORMS	Sat Oct 03 21:54:53 2020 +0200
@@ -50,8 +50,7 @@
 
 New (experimental):
 
-  arm64-linux       Ubuntu 20.04 LTS
-
+  arm64-linux       Raspberry Pi OS 64bit beta (Debian 10 / Buster)
 
 
 64 bit vs. 32 bit platform personality

--- a/Admin/components/components.sha1	Sat Oct 03 19:56:02 2020 +0200
+++ b/Admin/components/components.sha1	Sat Oct 03 21:54:53 2020 +0200
@@ -256,6 +256,7 @@
 7df4857d73dbc9edda25a6ad329e47639e70fadf  polyml-test-8fda4fd22441.tar.gz
 2b7c02b67feb2f44dda6938a7244f4257e7c580c  polyml-test-905dae2ebfda.tar.gz
 3dfdc58e5d9b28f038a725e05c9c2f2ce0bb2632  polyml-test-a3cfdf648da-1.tar.gz
+e2f075b0cc709f4f7f6492b725362f9010b2c6d1  polyml-test-a3cfdf648da-2.tar.gz
 33568f69ce813b7405386ddbefa14ad0342bb8f0  polyml-test-a3cfdf648da.tar.gz
 4bedaac4f1fb9a9199aa63695735063c47059003  polyml-test-a444f281ccec.tar.gz
 f3031692edcc5d8028a42861e4e40779f0f9d3e1  polyml-test-b68438d33c69.tar.gz

--- a/Admin/components/main	Sat Oct 03 19:56:02 2020 +0200
+++ b/Admin/components/main	Sat Oct 03 21:54:53 2020 +0200
@@ -12,7 +12,7 @@
 kodkodi-1.5.6
 nunchaku-0.5
 opam-2.0.7
-polyml-test-a3cfdf648da-1
+polyml-test-a3cfdf648da-2
 postgresql-42.2.9
 scala-2.12.12
 smbc-0.4.1