Write the array literal of all zeros as {0} rather than {}.

Change-Id: If15330d96d019be671d3bcbbdea60c2b3ecc2128
Reviewed-on: https://boringssl-review.googlesource.com/2740
Reviewed-by: Adam Langley <agl@google.com>

See https://tools.ietf.org/html/rfc5869.

Change-Id: I6d012d8c38806df80aa44350d3a86eaff499ac05
Reviewed-on: https://boringssl-review.googlesource.com/2533
Reviewed-by: Adam Langley <agl@google.com>