cmd/link: remove support for windows/arm relocations
The windows/arm port is no longer supported. We can remove the
related code from cmd/link/internal/arm.
For #71671
Change-Id: I00de1231482cc2f28ec5fc9dc62e81f0ba3fe481
Reviewed-on: https://go-review.googlesource.com/c/go/+/703778
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Cherry Mui <cherryyz@google.com> Reviewed-by: Than McIntosh <thanm@golang.org> Reviewed-by: Michael Knyszek <mknyszek@google.com>