cmd/link: make it compile again (fixes build)

CL 59375 changed Reloc.Done to bool, but that change
got lost in pe.go while merging. Restore that change.

Change-Id: Ie5a89e85579cdc9282f504fefd56355cfeb49389
Reviewed-on: https://go-review.googlesource.com/59711
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>

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

@@ -495,7 +495,7 @@ func (f *peFile) emitRelocations(ctxt *Link) {
 			}
 			for ri := 0; ri < len(sym.R); ri++ {
 				r := &sym.R[ri]
-				if r.Done != 0 {
+				if r.Done {
 					continue
 				}
 				if r.Xsym == nil {