Otherwise we get all these 'defined' symbols everywhere.

Change-Id: I4c21a4df8963146a79af3511a400f06698f1078a
Reviewed-on: https://boringssl-review.googlesource.com/4292
Reviewed-by: Adam Langley <agl@google.com>

skipPast got confused when STACK_OF wasn't in the front of the string (which it
rarely was due to OPENSSL_EXPORT).

It also couldn't parse comments which end with a '*/' on their own.
(Stylistically we don't do this, but ssl_cipher_preference_list_st ends with an
ASCII art diagram which probably shouldn't gain a comment marker in the middle.)

Change-Id: I7687f4fd126003108906b995da0f2cd53f7d693a
Reviewed-on: https://boringssl-review.googlesource.com/4288
Reviewed-by: Adam Langley <agl@google.com>

Also, set sensible defaults for the command-line arguments to doc.go.

Change-Id: Iefd2ade4c9095489efa0ae1059007593fc84923a

Add some missing headers and ensure each header has a short description. doc.go
gets confused at declarations that break before the first (, so avoid doing
that. Also skip a/an/deprecated: in markupFirstWord and process pipe words in
the table of contents.

Change-Id: Ia08ec5ae8e496dd617e377e154eeea74f4abf435
Reviewed-on: https://boringssl-review.googlesource.com/2839
Reviewed-by: Adam Langley <agl@google.com>

Initial fork from f2d678e6e8 (1.0.2 beta).

(This change contains substantial changes from the original and
effectively starts a new history.)