sk_X509_EXTENSION_delete returns X509_EXTENSION*
String literals are const char*.

GCC won't whine with -Wall because so much code isn't const correct but
writing to a string literal is undefined. -Wwrite-strings is the warning
flag to enable to spot these.
Merge pull request #366 from public/sk_X509_EXTENSION_delete-is-not-void

sk_X509_EXTENSION_delete returns X509_EXTENSION*
Merge pull request #365 from public/const-string-literal

String literals are const char*.
Merge pull request #364 from exarkun/certificates-and-stuff

expose SSL_get_peer_cert_chain, SSL_get_client_CA_list, and SSL_CTX_set_client_CA_list