Fix leak in setting certificate chain patch

Android has a custom certificate chain patch that didn't check whether
the cert_chain was already set when setting the new chain. This results
in a leak of all the X509 instances in the stack of certificates.

Bug: 10610037
Change-Id: I62433671ef18b06cafa5ec18e7b2e6190ce4504d
Add TLS 1.2 digests patch

Fixes a bug with handling TLS 1.2 and digest functions for DSA and ECDSA
keys.

Patch from Adam Langley <agl@chromium.org>

Change-Id: I11b74472c0df16eca8de3aa36413686603814243
Add ALPN support patch

This change adds support for ALPN[1] in OpenSSL. ALPN is the IETF
blessed version of NPN and we'll be supporting both ALPN and NPN for
some time yet.

[1] https://tools.ietf.org/html/draft-ietf-tls-applayerprotoneg-00

Patch from Adam Langley <agl@chromium.org>

Change-Id: I556b1ee877f398ae8b7f1d4abbaddc44611e5f51
Fix typo in OPENSSL_DIR_ORIG variable name.

Change-Id: I7d8b77d77979f69cbb5e63f1fcab802e9dcccfe0