lif: drop support for go1.5

This change drops a workaround for golang.org/issues/13372.

The compiler in Go 1.6 or above handles the "conversion of a
unsafe.Pointer to uintptr when calling syscall.Syscall" case
correctly.

Change-Id: I5b45094a78f15a631da277bbea0cb79fde25bb2a
Reviewed-on: https://go-review.googlesource.com/37170
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2 files changed