Mark platform specific svn_auth_get_* functions as deprecated to discourage
api consumers from using them and point them towards
svn_auth_get_platform_specific_provider().

* subversion/include/svn_auth.h
  (svn_auth_get_windows_simple_provider,
   svn_auth_get_windows_ssl_client_cert_pw_provider,
   svn_auth_get_windows_ssl_server_trust_provider,
   svn_auth_get_keychain_simple_provider,
   svn_auth_get_keychain_ssl_client_cert_pw_provider,
   svn_auth_get_gnome_keyring_simple_provider,
   svn_auth_get_gnome_keyring_ssl_client_cert_pw_provider,
   svn_auth_get_kwallet_simple_provider,
   svn_auth_get_kwallet_ssl_client_cert_pw_provider,
   svn_auth_get_gpg_agent_simple_provider): Deprecate

* subversion/libsvn_subr/auth.h
  (svn_auth__get_windows_simple_provider,
   svn_auth__get_windows_ssl_client_cert_pw_provider,
   svn_auth__get_windows_ssl_server_trust_provider,
   svn_auth__get_keychain_simple_provider,
   svn_auth__get_keychain_ssl_client_cert_pw_provider,
   svn_auth__get_gnome_keyring_simple_provider,
   svn_auth__get_gnome_keyring_ssl_client_cert_pw_provider,
   svn_auth__get_kwallet_simple_provider,
   svn_auth__get_kwallet_ssl_client_cert_pw_provider,
   svn_auth__get_gpg_agent_simple_provider): Add private delcartions.

* subversion/libsvn_subr/gpg_agent.c,
  subversion/libsvn_subr/macos_keychain.c,
  subversion/libsvn_subr/win32_crypto.c:
  (svn_auth__get_*): Convert public versions to private versions.

* subversion/libsvn_subr/deprecated.c
  (svn_auth_get_*): Implement public versions as wrappers of the new private
    versions.

* subversion/libsvn_subr/auth.c
  (svn_auth_get_platform_specific_provider): Use private versions
    of the platform specific svn_auth_get_* functions in order
    to avoid warnings about using deprecated functions.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1543992 13f79535-47bb-0310-9956-ffa450edef68