cmd/heapview: remove needless slash

Change-Id: Ie19a60595862c0afff9364ee21dd9598370e6c91
Reviewed-on: https://go-review.googlesource.com/38752
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
1 file changed