add libffi and elfutils as dependency for Clang v11.0.1 + v12.0.1

[bowentan]

(created using eb --new-pr)
Add libffi and elfutils as dependencies

[Micket]

lgtm (as discussed in slack, this was pretty clear cut; libomptarget.* dynamically links to both libffi and libelf)

[Micket]

Test report by @Micket
SUCCESS
Build succeeded for 4 out of 4 (2 easyconfigs in total)
alvis-s1 - Linux Rocky Linux 8.5, x86_64, Intel(R) Xeon(R) Silver 4314 CPU @ 2.40GHz, Python 3.6.8
See https://gist.github.com/eca7d5935f8a6db1035dec7c6bb5a013 for a full test report.

[Micket]

@boegelbot please test @ generoso

[boegelbot]

@Micket: Request for testing this PR well received on login1

PR test command 'EB_PR=15935 EB_ARGS= /opt/software/slurm/bin/sbatch --job-name test_PR_15935 --ntasks=4 ~/boegelbot/eb_from_pr_upload_generoso.sh' executed!

• exit code: 0
• output:

Submitted batch job 8930

Test results coming soon (I hope)...

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Message to humans: this is just bookkeeping information for me,
it is of no use to you (unless you think I have a bug, which I don't).

[boegelbot]

Test report by @boegelbot
SUCCESS
Build succeeded for 2 out of 2 (2 easyconfigs in total)
cns1 - Linux Rocky Linux 8.5, x86_64, Intel(R) Xeon(R) CPU E5-2667 v3 @ 3.20GHz (haswell), Python 3.6.8
See https://gist.github.com/f7aa9298ee64669ec086bf12daecab94 for a full test report.

[Micket]

Going in, thanks @bowentan!

[zdemat]

@bowentan and @Micket

can Clang-11.0.1-gcccuda-2020b.eb be fixed as well? It provides NVPTX target in addition.

[boegel]

I've made this fix consistent in recent Clang easyconfigs in #16225

[zdemat]

@boegel Then I am interested in the test result of #16225 for Clang11.0.1 as I reported a possible issue with the easyblock: fix sanity checks for Clang 11 when built with NVPTX support easyblocks/#2782

[boegel]

@zdemat I'll keep an eye out for that, thanks for the PR!