add missing Perl build dependency for Longshot

[boegel]

(created using eb --new-pr)
fixes failing build due to:

Can't locate IPC/Cmd.pm in @INC
...
Error configuring OpenSSL build

[boegel]

@boegelbot please test @ generoso
EB_ARGS="Longshot-0.4.3-GCCcore-10.2.0.eb"

[boegel]

I've applied this fix to all existing Longshot easyconfigs, because it's quite trivial.

But while testing I noticed that only Longshot-0.4.3-GCCcore-10.2.0.eb actually still works: the other Longshot easyconfigs fail to install with Rust compilation errors, probably because the latest version of the Rust packages that are downloaded automatically are no longer compatible with older the Rust version.

We should fix that by controlling the version of those Rust packages by installing them as extensions with EasyBuild (and also avoid the downloading on the fly), but that's a fun exercise for a later PR...

[boegelbot]

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

PR test command 'EB_PR=14535 EB_ARGS="Longshot-0.4.3-GCCcore-10.2.0.eb" /opt/software/slurm/bin/sbatch --job-name test_PR_14535 --ntasks=4 ~/boegelbot/eb_from_pr_upload_generoso.sh' executed!

• exit code: 0
• output:

Submitted batch job 7466

Test results coming soon (I hope)...

- notification for comment with ID 991570367 processed

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).

[boegel]

Test report by @boegel
SUCCESS
Build succeeded for 1 out of 1 (1 easyconfigs in total)
node2622.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/a5faf4b5a2d893addda331e6870099cc for a full test report.

[boegelbot]

Test report by @boegelbot
SUCCESS
Build succeeded for 1 out of 1 (1 easyconfigs in total)
cns1 - Linux rocky linux 8.4, x86_64, Intel(R) Xeon(R) CPU E5-2667 v3 @ 3.20GHz (haswell), Python 3.6.8
See https://gist.github.com/baf1abaf0b01ee6724cd9278640877d8 for a full test report.

[verdurin]

Looks fine.

[verdurin]

Going in, thanks @boegel!

[verdurin]

Test report by @verdurin
FAILED
Build succeeded for 44 out of 47 (4 easyconfigs in total)
centos7.lan - Linux centos linux 7.9.2009, x86_64, Intel Core Processor (Skylake, IBRS), Python 3.6.8
See https://gist.github.com/57f9a9fb2248be0984fd6ff584918a1e for a full test report.