Add support for cloning Google benchmark

[vyasr]

Description

Many RAPIDS libraries use Google benchmark to manage C++ benchmarks. This PR centralizes the dependency and the version management.

Resolves #288.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.
• The cmake-format.json is up to date with these changes.
• I have added new files under rapids-cmake/
  • I have added include guards (include_guard(GLOBAL))
  • I have added the associated docs/ rst file and update the api.rst

[vyasr]

I should add that cuML and cuGraph's current versions of this function specify the lib dir for gbench, but I don't think we need or want that. Please correct me if I'm wrong.

[robertmaynard]

Looks great. Just a couple of small changes needed

[robertmaynard]

I should add that cuML and cuGraph's current versions of this function specify the lib dir for gbench, but I don't think we need or want that. Please correct me if I'm wrong.

We will want to specify the install directory if INSTALL_EXPORT_SET is set. But we will want to use rapids_cmake_install_lib_dir to compute the correct location. I expect this was done so it doesn't go into something like lib64 and therefore breaks conda layout requirements.

[bdice]

No comments aside from what @robertmaynard mentioned. Nice, thanks for doing this!

[vyasr]

I should add that cuML and cuGraph's current versions of this function specify the lib dir for gbench, but I don't think we need or want that. Please correct me if I'm wrong.

We will want to specify the install directory if INSTALL_EXPORT_SET is set. But we will want to use rapids_cmake_install_lib_dir to compute the correct location. I expect this was done so it doesn't go into something like lib64 and therefore breaks conda layout requirements.

I'm now setting the CMAKE_INSTALL_LIBDIR for this target unconditionally (using rapids_cmake_install_lib_dir). I'm assuming that the BENCHMARK_ENABLE_INSTALL option for GBench will take care of whether installation happens at all so it should be safe to always set this.

[vyasr]

@robertmaynard are you happy with the current state of this PR?

[robertmaynard]

LGTM, thank you

[vyasr]

@gpucibot merge