Update the lif package to rev 7bf7a75.

Introduce the following changes:
 - 7bf7a75 lif: use of nativeEndian to make API endian agnostic
 - adc6ba9 lif: drop support for go1.5

Updates #19967

Change-Id: Iaba893b5ee9af4c54bf5ba4244ce5752ce9f6ad3
Reviewed-on: https://go-review.googlesource.com/40831Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>