ssl is all that's left. Will do that once that's at a quiet point.

Change-Id: Ia183aed5671e3b2de333def138d7f2c9296fb517
Reviewed-on: https://boringssl-review.googlesource.com/19564
Commit-Queue: David Benjamin <davidben@google.com>
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: Adam Langley <agl@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>

This is kind of a mess. Some projects will wrap our public headers in
extern "C", so we use extern "C++" around our C++ APIs. However this
needs to be done when including C++ standard library headers too since
they don't always, themselves, guard against being wrapped in extern
"C".

Change-Id: Ib7dd4a6f69ca81dd525ecaa1418b3b7ba85b6579
Reviewed-on: https://boringssl-review.googlesource.com/18504
Reviewed-by: Adam Langley <agl@google.com>

Change-Id: Id849061c63c954f915c8efd34838f867f8e1b09e
Reviewed-on: https://boringssl-review.googlesource.com/18384
Commit-Queue: Martin Kreichgauer <martinkr@google.com>
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: Adam Langley <agl@google.com>

This is a C++ interface for encrypting and decrypting TLS application
data records in-place, wrapping the existing C API in tls_record.cc.

Also add bssl::Span, a non-owning reference to a contiguous array of
elements which can be used as a common interface over contiguous
container types (like std::vector), pointer-length-pairs, arrays, etc.

Change-Id: Iaa2ca4957cde511cb734b997db38f54e103b0d92
Reviewed-on: https://boringssl-review.googlesource.com/18104
Commit-Queue: Martin Kreichgauer <martinkr@google.com>
Reviewed-by: Adam Langley <agl@google.com>