libClangSharp.runtime.* build instructions

[rokups]

Would it be possible to get build instructions for libClangSharp.runtime.* packages? CI does not build them.

[tannergooding]

CI does not currently build it because it is very expensive to do so.

The basic steps are essentially:

1. Clone https://github.com/llvm/llvm-project
2. Build a release configuration of llvm-project by following the instructions provided: http://clang.llvm.org/get_started.html
3. Install the built llvm-project to some folder (generally specified via CMAKE_INSTALL_PREFIX=path)
4. Using cmake, build libClangSharp. The cmakelist.txt is in the repo root and specifying PATH_TO_LLVM=path, where path is the same as specified for the llvm-project CMAKE_INSTALL_PREFIX

If on Linux, you may be able to skip steps 1-3 by setting PATH_TO_LLVM to something like /usr/lib/llvm-10, the need is to resolve lib/cmake/clang/ClangConfig.cmake and friends which aren't always available for a given install.

[tannergooding]

#214 adds some basic documentation on building the managed vs native sides.

Please feel free to request additional information or clarification if its needed and I'll work on updating the docs further.

[tannergooding]

See https://github.com/microsoft/ClangSharp#building-managed
and https://github.com/microsoft/ClangSharp#building-native