libssh 0.7.7

[chcg]

• reduced build config for libssh by switching off some unused parts via libssh cmake configs

• build multithreaded

• update to libssh 0.7.7 with: -- Fixed issues with MSVC -- Fixed keyboard-interactive auth in server mode (regression from CVE-2018-10933) -- Fixed gssapi auth in server mode (regression from CVE-2018-10933) -- Fixed a memory leak with OpenSSL

• update to libssh 0.7.6 with: -- Fixed CVE-2018-10933 -- Added support for OpenSSL 1.1 -- Added SHA256 support for ssh_get_publickey_hash() -- Fixed config parsing -- Fixed random memory corruption when importing pubkeys

[chcg]

Known remaining issue also for libssh 0.7.7 see https://bugs.libssh.org/T119, that also affects mingw builds used for deployment.