cmd/link: add time stamp to hostlink print in -v mode

Change-Id: I128b142aee5e1b917e7ba63b48512972f053ea0b
Reviewed-on: https://go-review.googlesource.com/29531
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Author: rsc

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

@@ -1147,7 +1147,7 @@ func (l *Link) hostlink() {
 	}
 
 	if l.Debugvlog != 0 {
-		l.Logf("host link:")
+		l.Logf("%5.2f host link:", obj.Cputime())
 		for _, v := range argv {
 			l.Logf(" %q", v)
 		}