cmd/go: (via go/build): a GOOS prefix acts as a tag only if preceded by an underscore. this is a breaking change. (CL 147690043)
asm: make textflag.h available outside of cmd/ld (CL 128050043)
+bufio: handling of empty tokens at EOF changed, may require scanner change (CL 145390043)
crypto/tls: add support for ALPN (RFC 7301) (CL 108710046)
crypto/tls: support programmatic selection of server certificates (CL 107400043)
fmt: print type *map[T]T as &map[k:v] (CL 154870043)