cmd/compile: special case coverage vars in pkg init order
When computing package initialization order, special case the counter
variables inserted by "cmd/cover" for coverage instrumentation, since
their presence can perturb the order in which variables are
initialized in ways that are user-visible and incorrect with respect
to the original (uninstrumented) program.
Fixes #56293.
Change-Id: Ieec9239ded4f8e2503ff9bbe0fe171afb771b335
Reviewed-on: https://go-review.googlesource.com/c/go/+/443715
Run-TryBot: Than McIntosh <thanm@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com> Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>