cmd/link: don't skip code sign even if dsymutil didn't generate a file
Even if dsymutil didn't generate a file (which should not happen
with the Apple toolchain with the correct setup), we should not
skip next steps, e.g. code sign. A return statement makes it exit
too early.
Updates #68088.
Change-Id: Ic1271ed1b7fe5bdee5a25cc5d669a105173b389e
Reviewed-on: https://go-review.googlesource.com/c/go/+/593660
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Than McIntosh <thanm@google.com>