ssl.h should be first. Also two lines after includes and the rest of the
file.

Change-Id: Icb7586e00a3e64170082c96cf3f8bfbb2b7e1611
Reviewed-on: https://boringssl-review.googlesource.com/5892
Reviewed-by: Adam Langley <agl@google.com>

Due to a typo, when a server sent an unknown extension, the extension
number would be taken from a NULL structure rather than from the
variable of the same name that's in the local scope.

BUG=517935

Change-Id: I29d5eb3c56cded40f6155a81556199f12439ae06
Reviewed-on: https://boringssl-review.googlesource.com/5650
Reviewed-by: Adam Langley <agl@google.com>

This change mirrors upstream's custom extension API because we have some
internal users that depend on it.

Change-Id: I408e442de0a55df7b05c872c953ff048cd406513
Reviewed-on: https://boringssl-review.googlesource.com/5471
Reviewed-by: Adam Langley <agl@google.com>