Merge branch 'ssl_config' into development

* ssl_config: (45 commits)
  Fix warning in ssl_pthread_server
  Fix dependency issues
  Fix typos in mini_client.c
  Optimize config usage in concurrent server examples
  Fix bug introduced when splitting init functions
  Fix order of ssl_conf vs ssl_setup in programs
  Update Changelog with forgotten change
  Change a few ssl_conf return types to void
  Update Changelog for recent config split
  Fix typos in the Changelog
  Rename ssl_set_xxx() to ssl_conf_xxx()
  Add ssl_set_hs_ca_chain()
  Make conf const inside ssl_context (finally)
  Change ssl_own_cert to work on ssl_config
  Add ssl_set_hs_own_cert()
  Rework ssl_set_own_cert() internals
  Change ssl_set_psk() to act on ssl_config
  Use a specific function in the PSK callback
  Make xxx_drbg_random() thread-safe
  Move ssl_set_rng() to act on config
  ...