[Originally written by nharper, tweaked by davidben.]

In TLS 1.3, every extension the server previously sent gets moved to a
separate EncryptedExtensions message. To be able to share code between
the two, parse those extensions separately. For now, the handshake reads
from serverHello.extensions.foo, though later much of the extensions
logic will probably handle serverExtensions independent of whether it
resides in ServerHello or EncryptedExtensions.

Change-Id: I07aaae6df3ef6fbac49e64661d14078d0dbeafb0
Reviewed-on: https://boringssl-review.googlesource.com/8584


Reviewed-by: David Benjamin <[email protected]>