internal/cpu: more build fixes for Go1.16beta1 release

Some files were missing from the libgo copy of internal/cpu, because they
used to only declare CacheLinePadSize which libgo gets from goarch.sh.
Now they also declare doinit, so copy them over.  Adjust cpu_other.go.

Fix the amd64p32 build by adding a build constraint to cpu_no_name.go.

Fixes https://gcc.gnu.org/PR98493

Change-Id: I32fd4395096cff2017b2d0a9a3d85edc03d46590
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/281472
Trust: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
9 files changed