update Clang easyblock to add support for building extra tools + leveraging hwloc and Z3 as optional dependencies

[geimer]

Add support for building the extra Clang tools, and optionally configuring use of hwloc by the OpenMP runtime, and Z3 bei the Clang static analyzer.

[ocaisa]

LGTM, might be a while before generoso can build and test this on the open easyconfig PR

[ocaisa]

Minor comment

requested change made

[boegel]

lgtm

[boegel]

Test report by @boegel

Overview of tested easyconfigs (in order)

• SUCCESS Clang-6.0.1-GCC-6.4.0-2.28.eb
• SUCCESS Clang-9.0.1-GCCcore-8.3.0.eb
• SUCCESS Clang-11.0.0-GCCcore-9.3.0.eb

Build succeeded for 3 out of 3 (3 easyconfigs in total)
node2606.swalot.os - Linux centos linux 7.9.2009, x86_64, Intel(R) Xeon(R) CPU E5-2660 v3 @ 2.60GHz (haswell), Python 3.6.8
See https://gist.github.com/d6647eac4099662c5fe21d21288b2ded for a full test report.

[boegel]

Test report by @boegel

Overview of tested easyconfigs (in order)

• SUCCESS Clang-6.0.1-GCC-6.4.0-2.28.eb
• SUCCESS Clang-8.0.0-GCCcore-8.2.0.eb
• SUCCESS Clang-10.0.0-GCCcore-9.3.0.eb

Build succeeded for 3 out of 3 (3 easyconfigs in total)
node3136.skitty.os - Linux centos linux 7.9.2009, x86_64, Intel(R) Xeon(R) Gold 6140 CPU @ 2.30GHz, Python 3.6.8
See https://gist.github.com/daf600641cb99b7c905a7d355ed0615a for a full test report.