message: add GINKGO_BUILD_HWLOC in INTSALL.md
diff: @@ -41,6 +41,8 @@ Ginkgo adds the following additional switches to control what is being built:
  `OFF` otherwise.
  * `-DGINKGO_HIP_AMDGPU="gpuarch1;gpuarch2"` the amdgpu_target(s) variable
  passed to hipcc for the `hcc` HIP backend. The default is none (auto).
  +* `-DGINKGO_BUILD_HWLOC={ON, OFF}` builds Ginkgo with HWLOC. If system HWLOC
  + is not found, Ginkgo will try to build it. Default is `ON`.
  * `-DGINKGO_BUILD_DOC={ON, OFF}` creates an HTML version of Ginkgo's documentation
  from inline comments in the code. The default is `OFF`.
  * `-DGINKGO_DOC_GENERATE_EXAMPLES={ON, OFF}` generates the documentation of examples
  @@ -246,13 +248,17 @@ packages can be turned off by disabling the relevant options.
  + GINKGO_DEVEL_TOOLS=ON:
  [git-cmake-format](https://github.com/gflegar/git-cmake-format) is our CMake
  helper for code formatting.
  ++ GINKGO_BUILD_HWLOC=ON:
  + [hwloc](https://www.open-mpi.org/projects/hwloc) to help us to control cores
  + and devices.
  -By default, Ginkgo uses the internal version of each package. For each of the
  +Usually, Ginkgo uses the internal version of each package. For each of the
  packages `GTEST`, `GFLAGS`, `RAPIDJSON` and `CAS`, it is possible to force
  Ginkgo to try to use an external version of a package. For this, Ginkgo provides
  two ways to find packages. To rely on the CMake `find_package` command, use the
  -CMake option `-DGINKGO_USE_EXTERNAL_<package>=ON`. Note that, if the external
  -packages were not installed to the default location, the CMake option
  +CMake option `-DGINKGO_USE_EXTERNAL_<package>=ON`. `HWLOC` always looks for
  +system `HWLOC` first currently. Note that, if the external packages were not
  +installed to the default location, the CMake option
  `-DCMAKE_PREFIX_PATH=<path-list>` needs to be set to the semicolon (`;`)
  separated list of install paths of these external packages. For more
  Information, see the [CMake documentation for
  