config.guess and IBM Z

The script queries the output of uname, which is on the machine I test 
on (IBM Z with Unix System Services USS):

OS/390 S0W1 29.00 05 3931

because of OS/390 the script sets

     *:OS/390:*:*)
	GUESS=i370-ibm-openedition

The vendor ibm is correct, the os "openedition" _may_ be fine, but the 
cpu type is definitely not correct, standing for the 32bit mainframe 
architecture System/370 from 1970.


Instead, the cpu 3931 is part of the IBM Z architecture (z16, "Telum" 
from 2022).

Maybe _if_ there is any cpu part just place it in there (or do a mapping 
to zNN) or use a place holder like ibmZ?


See https://en.wikipedia.org/wiki/IBM_Z
https://www.redbooks.ibm.com/redbooks/pdfs/sg248951.pdf
https://www.nextplatform.com/2024/08/27/ibm-shows-off-next-gen-ai-acceleration-on-chip-dpu-for-big-iron/