cmd/link: extract windows-specific code from dynrelocsym

No functional changes.

Change-Id: Ib31bb3f01b515aac6428ec61e0ef02b269623890
Reviewed-on: https://go-review.googlesource.com/62470Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

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

@@ -759,8 +759,7 @@ func (ctxt *Link) reloc() {
 	}
 }
 
-func dynrelocsym(ctxt *Link, s *Symbol) {
-	if Headtype == objabi.Hwindows && Linkmode != LinkExternal {
+func windynrelocsym(ctxt *Link, s *Symbol) {
 	rel := ctxt.Syms.Lookup(".rel", 0)
 	if s == rel {
 		return
@@ -801,7 +800,11 @@ func dynrelocsym(ctxt *Link, s *Symbol) {
 			r.Add = int64(targ.Plt)
 		}
 	}
+}
 
+func dynrelocsym(ctxt *Link, s *Symbol) {
+	if Headtype == objabi.Hwindows && Linkmode != LinkExternal {
+		windynrelocsym(ctxt, s)
 		return
 	}