clean up GCC-related options for full-LLVM build

[Flamefire]

This is purely a refactoring without any behavior change

• Add comment what the option dict is used for: Only for dependency-less (builds when full_llvm=True)
• Remove condition on full_llvm when setting such options.
• Remove some commented code. The comments on where they have been moved to are better suited for the commit / PR description, aren't they?

Closes #3826

[Flamefire]

Test report by @Flamefire

Overview of tested easyconfigs (in order)

• SUCCESS LLVM-19.1.7-GCCcore-13.3.0.eb
• SUCCESS LLVM-20.1.5-GCCcore-13.3.0.eb
• FAIL (build issue) LLVM-18.1.8-GCCcore-13.3.0.eb (partial log available at https://gist.github.com/Flamefire/43302f7ff41c77d52f462cb560333227)

Build succeeded for 2 out of 3 (3 easyconfigs in total)
n1079 - Linux RHEL 8.9 (Ootpa), x86_64, Intel(R) Xeon(R) Platinum 8470 (sapphirerapids), Python 3.9.18
See https://gist.github.com/Flamefire/a897319fccf89961cdea6b7d64d0b40d for a full test report.

[Flamefire]

Test report by @Flamefire

Overview of tested easyconfigs (in order)

• SUCCESS LLVM-19.1.7-GCCcore-13.3.0.eb
• SUCCESS LLVM-20.1.5-GCCcore-13.3.0.eb
• SUCCESS LLVM-18.1.8-GCCcore-13.3.0.eb

Build succeeded for 3 out of 3 (3 easyconfigs in total)
c83 - Linux AlmaLinux 9.4, x86_64, AMD EPYC 9334 32-Core Processor (zen4), 4 x NVIDIA NVIDIA H100, 560.35.03, Python 3.9.18
See https://gist.github.com/Flamefire/da7014d708d8f52d333f74ab4d32c14b for a full test report.

[Flamefire]

Test report by @Flamefire

Overview of tested easyconfigs (in order)

• SUCCESS LLVM-19.1.7-GCCcore-13.3.0.eb
• SUCCESS LLVM-20.1.5-GCCcore-13.3.0.eb
• SUCCESS LLVM-18.1.8-GCCcore-13.3.0.eb

Build succeeded for 3 out of 3 (3 easyconfigs in total)
i7184 - Linux Rocky Linux 8.9 (Green Obsidian), x86_64, AMD EPYC 7702 64-Core Processor (zen2), Python 3.9.18
See https://gist.github.com/Flamefire/f138c1d21a86e25fbe301f1191b229c3 for a full test report.

[Crivella]

Got conflicts after merging #3825

[Flamefire]

Resolved with merge

[Crivella]

@boegelbot please test @ jsc-zen3
EB_ARGS="LLVM-18.1.8-GCCcore-13.3.0.eb LLVM-19.1.7-GCCcore-13.3.0.eb LLVM-20.1.5-GCCcore-13.3.0.eb"
CORE_CNT=16

[boegelbot]

@Crivella: Request for testing this PR well received on jsczen3l1.int.jsc-zen3.fz-juelich.de

PR test command 'if [[ develop != 'develop' ]]; then EB_BRANCH=develop ./easybuild_develop.sh 2> /dev/null 1>&2; EB_PREFIX=/home/boegelbot/easybuild/develop source init_env_easybuild_develop.sh; fi; EB_PR=3827 EB_ARGS="LLVM-18.1.8-GCCcore-13.3.0.eb LLVM-19.1.7-GCCcore-13.3.0.eb LLVM-20.1.5-GCCcore-13.3.0.eb" EB_REPO=easybuild-easyblocks EB_BRANCH=develop /opt/software/slurm/bin/sbatch --job-name test_PR_3827 --ntasks="16" ~/boegelbot/eb_from_pr_upload_jsc-zen3.sh' executed!

• exit code: 0
• output:

Submitted batch job 7166

Test results coming soon (I hope)...

Details

- notification for comment with ID 3047843586 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).

[Flamefire]

Test report by @Flamefire

Overview of tested easyconfigs (in order)

• SUCCESS LLVM-19.1.7-GCCcore-13.3.0.eb
• SUCCESS LLVM-20.1.5-GCCcore-13.3.0.eb
• FAIL (build issue) LLVM-18.1.8-GCCcore-13.3.0.eb (partial log available at https://gist.github.com/Flamefire/710cfdf9c3eab920fb027cecfacef875)

Build succeeded for 2 out of 3 (3 easyconfigs in total)
n1577 - Linux RHEL 8.9 (Ootpa), x86_64, Intel(R) Xeon(R) Platinum 8470 (sapphirerapids), Python 3.9.18
See https://gist.github.com/Flamefire/0d95815dee21b1dd377abccde4358824 for a full test report.

[boegelbot]

Test report by @boegelbot

Overview of tested easyconfigs (in order)

• SUCCESS LLVM-18.1.8-GCCcore-13.3.0.eb
• SUCCESS LLVM-19.1.7-GCCcore-13.3.0.eb
• SUCCESS LLVM-20.1.5-GCCcore-13.3.0.eb

Build succeeded for 3 out of 3 (3 easyconfigs in total)
jsczen3c1.int.jsc-zen3.fz-juelich.de - Linux Rocky Linux 9.5, x86_64, AMD EPYC-Milan Processor (zen3), Python 3.9.21
See https://gist.github.com/boegelbot/c8d64d397db1a8ebc8d6fbd3cc621ef4 for a full test report.

[Crivella]

LGTM

[Crivella]

Going in, thanks @Flamefire!