New CPUTYPE default for i386 port

[Rebecca Cran]

> On Oct 5, 2019, at 9:23 PM, Rodney W. Grimes <freebsd-rwg at gndrsh.dnsmgr.net> wrote:
> 
> 586 == Pentium I, almost all, if not all chipsets in the family support
> 128MB, and many supported 192 to 512MB.

Though many couldn’t cache more than 64MB. 

From https://www.vogonswiki.com/index.php/Socket_7_Builds
“It's a common mistake to load up 430FX, 430VX and 430TX chip sets with maximum amount of memory supported by the chipset. With these chip sets, the use of more than 64MB of RAM results in a significant performance drop, as memory bandwidth over 64MB is considerably reduced resulting in about 40% system performance compared to working with L2-cached RAM. To avoid this, either remove extra RAM, or change motherboard for a 430HX based one. If specific applications require more RAM, it could be worthwhile to cover the RAM above 64 MB when using DOS by loading a RAM drive to the remaining top memory area. Some chip sets from other manufacturers are also known to cache more than 64 MB RAM.”

— 
Rebecca Cran