libgo: update x/sys/cpu to add all GOARCHes supported by gccgo
libgo: update x/sys/cpu to add all GOARCHes supported by gccgo

CL 237897 added additional GOARCHes supported by gccgo to x/sys/cpu.

Change-Id: If1129bf404fd3fbf18ae4400c1445b79f4671c46
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/238038
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

golang/gofrontend,golang/gofrontend,golang/gofrontend,golang/gofrontend