[Cling] Add Windows CI to Github Actions

[reikdas]

It seems independent Cling builds have been broken on Windows for a while (or am making an error when setting up the build in Cling's Github Actions CI?)

Looking at Cling commits - https://github.com/root-project/cling/commits/master it looks like Cling's appveyor hasn't even triggered in a long time, so it is difficult to say when was the last time that an independent Cling built worked on Windows.

I made some attempt to fix it via - https://github.com/root-project/root/pull/6750/commits/db80e8c0038ab830b1cc4e7d2d42ad640c1ec232 but that is clearly not enough.

One can look at the build error logs on Windows in the corresponding Github Action workflow - https://github.com/reikdas/cling-1/runs/1348031890?check_suite_focus=true

@vgvassilev @bellenot Do you have any idea what could be going wrong?

If Cling can be built successfully on Windows, we can merge this in :D

[phsft-bot]

Starting build on ROOT-debian10-i386/cxx14, ROOT-performance-centos8-multicore/default, ROOT-fedora30/cxx14, ROOT-fedora31/noimt, ROOT-ubuntu16/nortcxxmod, mac1014/python3, mac1015/cxx17, windows10/cxx14 How to customize builds

[phsft-bot]

Build failed on ROOT-debian10-i386/cxx14. Running on pcepsft10.dyndns.cern.ch:/build/workspace/root-pullrequests-build See console output.

Errors:

• [2020-11-03T16:46:28.741Z] CMake Error at /home/sftnight/build/workspace/root-pullrequests-build/rootspi/jenkins/root-build.cmake:1002 (message):

[phsft-bot]

Build failed on ROOT-fedora31/noimt. Running on root-fedora-31-1.cern.ch:/build/workspace/root-pullrequests-build See console output.

Errors:

• [2020-11-03T16:46:46.163Z] CMake Error at /usr/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:164 (message):
• [2020-11-03T16:46:46.686Z] CMake Error at /build/workspace/root-pullrequests-build/rootspi/jenkins/root-build.cmake:1070 (message):

[phsft-bot]

Build failed on windows10/cxx14. Running on null:C:\build\workspace\root-pullrequests-build See console output.

Errors:

• [2020-11-03T17:10:00.474Z] LINK : fatal error LNK1181: cannot open input file 'cladPlugin.lib' [C:\build\workspace\root-pullrequests-build\build\core\metacling\src\Cling.vcxproj]

[phsft-bot]

Starting build on ROOT-debian10-i386/cxx14, ROOT-performance-centos8-multicore/default, ROOT-fedora30/cxx14, ROOT-fedora31/noimt, ROOT-ubuntu16/nortcxxmod, mac1014/python3, mac1015/cxx17, windows10/cxx14 How to customize builds

[reikdas]

Since we removed the Ninja build on Windows, the issue we need to solve right now is how to fix the failing Cling tests on Windows - https://github.com/reikdas/cling-1/runs/1353774432?check_suite_focus=true#step:7:9589. I tried to fix it via https://github.com/root-project/root/pull/6750/commits/21ffc04f200086da7c6127cccac3b4e18081eff0 but that did not work :(

[phsft-bot]

Build failed on windows10/cxx14. Running on null:C:\build\workspace\root-pullrequests-build See console output.

Failing tests:

• projectroot.tree.dataframe.test.gtest_tree_dataframe_test_dataframe_concurrency

[guitargeek]

We have Windows build on the CI every time now, dunno why this PR is needed! In case I'm wrong, feel free to reopen it :slightly_smiling_face:

[pcanal]

This is about the Cling specific CI. @vgvassilev do you want to review this PR or to close it?

[vgvassilev]

This is not a bad change. It needs some more work but I think @reikdas has moved on and I do not have the bandwidth to do it...