[dev.boringcrypto] all: merge master (more nearly Go 1.10 beta 1) into dev.boringcrypto

This merge picks up the new marshal tests in package hash.

Change-Id: I50136ad4953c64d776d28f13b37470ea884cb8dd

diff --cc src/crypto/sha1/sha1.go
Simple merge

diff --cc src/crypto/sha1/sha1_test.go
Simple merge

diff --cc src/crypto/sha256/sha256.go
Simple merge

diff --cc src/crypto/sha512/sha512.go
Simple merge