Allow user-defined settings without editing header files by using
POLARSSL_CONFIG_OPTIONS in config.h
(cherry picked from commit 6fa5488779c5b50bf13f9250e19d25c6c6cf9bcf)
Conflicts:
include/polarssl/config.h
The real peer certificate is copied into a x509_buf in the
ssl_cache_entry and reinstated upon cache retrieval. The information
about the rest of the certificate chain is lost in the process.
As the handshake (and certificate verification) has already been
performed, no issue is foreseen.
