fix dependencies and configure flags of GnuTLS 3.7.x

[Flamefire]

(created using eb --new-pr)

The GnuTLS builds could pick up system libraries instead of EasyBuild ones leading to failures later on, see e.g. #18288

It might also not pick up an EasyBuild dependency, like libidn.

Use --with- and --without- flags when available to enable/disable the dependencies.

Also add the missing pkgconf dependency and use libidn2 instead of the (ignored) libidn, see https://github.com/gnutls/gnutls/blob/3.7.2/configure.ac#L615

Closes #18288

[sassy-crick]

Test report by @sassy-crick
SUCCESS
Build succeeded for 3 out of 3 (3 easyconfigs in total)
hp - Linux Debian GNU/Linux 11, x86_64, 11th Gen Intel(R) Core(TM) i7-1185G7 @ 3.00GHz, Python 3.9.2
See https://gist.github.com/sassy-crick/bd1629fe9cbf356b57b5f810a89490e2 for a full test report.

[Flamefire]

Test report by @Flamefire
SUCCESS
Build succeeded for 5 out of 5 (3 easyconfigs in total)
taurusml2 - Linux RHEL 7.6, POWER, 8335-GTX, 6 x NVIDIA Tesla V100-SXM2-32GB, 440.64.00, Python 2.7.5
See https://gist.github.com/Flamefire/c5139fc77b9640372e7629be9253e1a1 for a full test report.

[sassy-crick]

@boegelbot please test @ generoso

[boegelbot]

@sassy-crick: Request for testing this PR well received on login1

PR test command 'EB_PR=19070 EB_ARGS= EB_CONTAINER= EB_REPO=easybuild-easyconfigs /opt/software/slurm/bin/sbatch --job-name test_PR_19070 --ntasks=4 ~/boegelbot/eb_from_pr_upload_generoso.sh' executed!

• exit code: 0
• output:

Submitted batch job 12047

Test results coming soon (I hope)...

- notification for comment with ID 1777370089 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).

[boegelbot]

Test report by @boegelbot
SUCCESS
Build succeeded for 3 out of 3 (3 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/boegelbot/100c096a420e743143caa41a15f2c412 for a full test report.

[Flamefire]

@sassy-crick Any update?

[ocaisa]

@boegelbot please test @ generoso
EB_ARGS="--include-easyblocks-from-pr 3026"

[boegelbot]

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

PR test command 'EB_PR=19070 EB_ARGS="--include-easyblocks-from-pr 3026" EB_CONTAINER= EB_REPO=easybuild-easyconfigs /opt/software/slurm/bin/sbatch --job-name test_PR_19070 --ntasks=4 ~/boegelbot/eb_from_pr_upload_generoso.sh' executed!

• exit code: 0
• output:

Submitted batch job 12996

Test results coming soon (I hope)...

- notification for comment with ID 1971317059 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).

[boegelbot]

Test report by @boegelbot
Using easyblocks from PR(s) easybuilders/easybuild-easyblocks#3026
SUCCESS
Build succeeded for 3 out of 3 (3 easyconfigs in total)
cns3 - Linux Rocky Linux 8.9, x86_64, Intel(R) Xeon(R) CPU E5-2667 v3 @ 3.20GHz (haswell), Python 3.6.8
See https://gist.github.com/boegelbot/da560b4461ad6f78112d2f32fc5e803d for a full test report.