Fix failing Windows build

[marcelwa]

Trying to compile with different toolsets under Windows reveals compilation errors. I will open a separate issue pointing to this PR.

[marcelwa]

As mentioned in #531, this PR fixes a couple of compilation errors on Windows. If you want, you could merge this PR now. Do you want me to revert the changes I made to your Windows CI? They were only intended to showcase the problem.

[lee30sonia]

Are these toolsets commonly-used ones? If so, I think we can keep them.

[marcelwa]

I believe v142 is the default in Visual Studio 2019. I thought it would be beneficial to additionally test with Clang via the ClangCL toolset.

[lee30sonia]

Looks good to me. Could you please resolve the conflict (keeping yours) so that I can merge it? Thanks!

[lee30sonia]

@aletempiac FYI since your code is affected

[codecov-commenter]

Codecov Report

Merging #530 (c9eeb4f) into master (f427196) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #530   +/-   ##
=======================================
  Coverage   82.61%   82.61%           
=======================================
  Files         146      146           
  Lines       18099    18099           
=======================================
  Hits        14953    14953           
  Misses       3146     3146           

Impacted Files	Coverage Δ
include/mockturtle/utils/tech_library.hpp	84.58% <ø> (ø)

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