[dev.link] cmd/link: move some work after deadcode

This is in preparation of delaying loading symbol content to
after dead code elimination.

Change-Id: Ia4ce82d9a42cc1a76c82f6d0eb9a54b0325ee3ba
Reviewed-on: https://go-review.googlesource.com/c/go/+/197061
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>

src/cmd/link/internal/ld/main.go

@@ -208,9 +208,10 @@ func Main(arch *sys.Arch, theArch Arch) {
 	}
 	ctxt.loadlib()
 
-	ctxt.dostrdata()
 	deadcode(ctxt)
-	//ctxt.dumpsyms() // XXX
+	ctxt.linksetup()
+	ctxt.dostrdata()
+
 	dwarfGenerateDebugInfo(ctxt)
 	if objabi.Fieldtrack_enabled != 0 {
 		fieldtrack(ctxt)