[gsl-lite] Update to version 0.36.0

[mbeutel]

• What does your PR fix?

  This PR updates the version of gsl-lite to 0.36.0, cf. https://github.com/gsl-lite/gsl-lite/releases/tag/v0.36.0.

  gsl-lite recently moved to a new location, https://github.com/gsl-lite/gsl-lite/. This PR also updates the URL to point to the new location of the library.

  The previous portfile simply obtained the "gsl-lite.hpp" header file and deployed it to "${CURRENT_PACKAGES_DIR}/include". The new portfile now uses proper CMake installation instead of just deploying the header file, which has the following benefits:

  • the header is now installed to the correct location (<gsl/gsl-lite.hpp> rather than <gsl-lite.hpp>)
  • the additional header <gsl-lite/gsl-lite.hpp> is also installed
  • the imported CMake targets gsl::gsl-lite, gsl::gsl-lite-v0, and gsl::gsl-lite-v1 are now accessible to other projects via find_package()

  The new portfile still generates the legacy header <gsl-lite.hpp>, but it produces a diagnostic and simply forwards to the proper header <gsl/gsl-lite.hpp>:

  #ifndef GSL_LITE_HPP_VCPKG_COMPAT_HEADER_INCLUDED
  #define GSL_LITE_HPP_VCPKG_COMPAT_HEADER_INCLUDED
  #pragma message("The header <gsl-lite.hpp> is deprecated; please include <gsl/gsl-lite.hpp> instead.")
  #include <gsl/gsl-lite.hpp>
  #endif // GSL_LITE_HPP_VCPKG_COMPAT_HEADER_INCLUDED

• Which triplets are supported/not supported? All triplets should be supported. Have you updated the CI baseline? No.

• Does your PR follow the maintainer guide? Yes (I think)

[mbeutel]

Sorry for the drive-by patch to telnetpp in this PR; among other things, this patch makes telnetpp include <gsl/gsl-lite.hpp> rather than <gsl-lite.hpp>, which avoids the deprecation warning, but that makes it depend on the preceding changes to gsl-lite.

---

The linux builds for "cctz", "clblas", "discord-rpc", "matroska" all fail with the same message which seems unrelated to this PR:

/usr/include/pthread.h:399:12: error: ‘cpu_set_t’ does not name a type
      const cpu_set_t *__cpuset)
            ^~~~~~~~~

[vicroms]

Thanks for the PR!