Compilation fails with recent versions of libssh

[ttosttos]

YDK compilation fails with version libssh 0.8.0 or later. Note that the library is now at 0.9.5 as of Oct 2020 and most systems (e.g. MacOS, Ubuntu, etc.) now ship with libssh versions that YDK can't handle. Fix will require to update libnetconfg or migrate to libnetconf2 (see issue).

Logs

$ python3 generate.py --core --cpp
-- The C compiler identification is GNU 9.3.0
-- The CXX compiler identification is GNU 9.3.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake System: Ubuntu
-- Found LibXml2: /usr/lib/x86_64-linux-gnu/libxml2.so (found version "2.9.10") 
Set libyang plugin installation directory to: lib/libyang
-- Could NOT find Doxygen (missing: DOXYGEN_EXECUTABLE) 
CMake Error: The following variables are used in this project, but they are set to NOTFOUND.
Please set them or make sure they are set and tested correctly in the CMake files:
ssh_threads_location
    linked by target "ydk" in directory /home/vagrant/ydk-gen/gen-api/cpp/ydk

-- Configuring incomplete, errors occurred!
See also "/home/vagrant/ydk-gen/gen-api/cpp/ydk/build/CMakeFiles/CMakeOutput.log".

ERROR: Failed to configure build!

$

[ygorelik]

Duplicate of #826.