api: add openbsd syscall constants

Change-Id: I3ec00dac5e7d0e6dcafb7d65851bc53e0661c2b6
Reviewed-on: https://go-review.googlesource.com/34500
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

api: promote next.txt to go1.8.txt, update go tool

Change-Id: I37f2893ce14009efe095aac3bc811d650c66bf2a
Reviewed-on: https://go-review.googlesource.com/33761
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

[release-branch.go1.7] go1.7.4

Change-Id: I76d2c823eb98c16bb923caad2d0b0e0809a5ee37
Reviewed-on: https://go-review.googlesource.com/33798
Run-TryBot: Chris Broadfoot <cbro@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

[release-branch.go1.6] go1.6.4

Change-Id: I2deb44b5ba64e0838cf15f79aebc911ee38f6954
Reviewed-on: https://go-review.googlesource.com/33797
Run-TryBot: Chris Broadfoot <cbro@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

[release-branch.go1.7] go1.7.3

Change-Id: I906070c84c0f40c4dd8af8b5894895127834ee00
Reviewed-on: https://go-review.googlesource.com/31438
Run-TryBot: Chris Broadfoot <cbro@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

[release-branch.go1.7] go1.7.2

Change-Id: I546e8b1aa4facdbf13bb80d386bf4839a3aff9d1
Reviewed-on: https://go-review.googlesource.com/31314
Run-TryBot: Chris Broadfoot <cbro@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Chris Broadfoot <cbro@golang.org>

[release-branch.go1.7] go1.7.1

Change-Id: Id877244fba01ae84255ad2d1f6334d096d5d6f71
Reviewed-on: https://go-review.googlesource.com/28694
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

go1.7

Change-Id: Id86f2615772ce087c2ac1a9039ffc27c33298773
Reviewed-on: https://go-review.googlesource.com/27075
Run-TryBot: Chris Broadfoot <cbro@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

go1.7rc6

Change-Id: Ie76b5af0ecc4c64c523110b44483c06e7031237c
Reviewed-on: https://go-review.googlesource.com/25582
Reviewed-by: Chris Broadfoot <cbro@golang.org>

go1.7rc5

Change-Id: I5571a5fa679065060950c554f7b28e42268b3e74
Reviewed-on: https://go-review.googlesource.com/25417
Run-TryBot: Chris Broadfoot <cbro@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>