Completes the WIP CMake config for find_package

[ilumsden]

The big thing this PR does is complete @JaeseungYeom's WIP DYADConfig.cmake and similar stuff for exporting DYAD and making it compatible with find_package(DYAD CONFIG).

It also does the following more minor things:

• Makes the naming of install path variables (e.g., DYAD_INSTALL_INCLUDE_DIR) more consistent and tweaks the values to be more consistent with expected behavior for installation paths
• Replaces the glibc version check with a portable version
• Replaces the CMake targets that added -Werror with a macro that will directly add the flag to targets with target_compile_options

In case we want to revert any of these changes, this PR currently does not delete any of the old code. Instead, the old code is just all commented out.

These changes have all been tested with the unit testing from the in-progress refactor/enhancement of the A4MD benchmark. Thanks to that, I can confirm that these changes allow external projects to properly use DYAD as a dependency with find_package.

[ilumsden]

This PR has been rebased on top of #117. It should only be merged once #117 is merged

[ilumsden]

This PR is ready for review @hariharan-devarajan @JaeseungYeom. Just note that it shouldn't be merged before #117

[JaeseungYeom]

Was this the PR that had ${CMAKE_INSTALL_PREFIX}/ removed?
We had a discussion on either testing to make sure linking is not broken with dynamic libraries or put it back.

[ilumsden]

@JaeseungYeom @hariharan-devarajan I've updated this PR to undo the removal of CMAKE_INSTALL_PREFIX in places. I still need to test that I can still use this to find DYAD in another CMake project, but this PR should be ready to discuss in our meeting on Thursday.

[hariharan-devarajan]

Some minor comments.

[ilumsden]

@hariharan-devarajan @JaeseungYeom tests with A4X-Benchmark were successful. I'll make the last couple of minor edits that @hariharan-devarajan suggested, and then this PR is fully ready for final review and merge.

[ilumsden]

@ilumsden double check that links/rpath is set correctly by running ldd

[ilumsden]

@ilumsden double check that links/rpath is set correctly by running ldd

RPATH is set correctly. When building with Spack, I get the following:

RPATH                /usr/WS2/lumsden1/spack/opt/spack/linux-rhel8-zen/gcc-10.3.1/dyad-cmake_export-l55ylmzb6eam427yrwgacppqpg3if2m5/lib64:/usr/WS2/lumsden1/spack/opt/spack/linux-rhel8-zen/gcc-10.3.1/dyad-cmake_export-l55ylmzb6eam427yrwgacppqpg3if2m5/lib64:/usr/WS2/lumsden1/spack/opt/spack/linux-rhel8-zen/gcc-10.3.1/gcc-runtime-10.3.1-jzsuaszeq4v63m2mgk3ccsbokplmvaxm/lib:/collab/usr/global/tools/tce4/packages/gcc/gcc-10.3.1/lib/gcc/x86_64-redhat-linux/10

The last 3 paths are injected by Spack. The first path is coming from DYAD's CMake.

[hariharan-devarajan]

Comments for -FPIC.

Remove the commented target properties.

[ilumsden]

@hariharan-devarajan @JaeseungYeom all the comments from yesterday have been addressed. I just have to rebase.

[wangvsa]

@ilumsden I need to merge this one before #120. Is this one ready?