cmd/compile: remove special treatment for cover vars in initorder
This patch reverts a portion of the changes in CL 443715, specifically
the code in initorder that treats coverage counter variables as special
with respect to init order. The special casing is no longer needed
now after a change to the way coverage instrumention is done (the go and
cover cmds now make sure that coverage variables appear first in
the compilation order).
Updates #56293.
Change-Id: Idf803ff4c1a095e88d455a6adcd63991687eb288
Reviewed-on: https://go-review.googlesource.com/c/go/+/499216
Run-TryBot: Than McIntosh <thanm@google.com> Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Matthew Dempsky <mdempsky@google.com>