ipv4: fix unsafe pointer conversion in parseInterface
ipv4: fix unsafe pointer conversion in parseInterface

Fixes golang/go#35174

Change-Id: I01ae0ec25c90da0d05b1b262b33a32233f88260f
Reviewed-on: https://go-review.googlesource.com/c/net/+/203400
Run-TryBot: Cuong Manh Le <54b4457f1dff6823379654eb5867596497ba782f@gmail.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

golang/net