Allow FlexiBLAS to link to MKL with LLVM

[bartoldeman]

LLVM flang follows gfortran for complex return values, but its OpenMP library libomp.so is compatible with Intel's.

requires:

• Implementing a new LLVM based toolchain easybuild-framework#4914

[boegel]

@boegelbot please test @ jsc-zen3
CORE_CNT=16
EB_ARGS="--installpath /tmp/$USER/pr3997 FlexiBLAS-3.3.1-GCC-12.3.0.eb FlexiBLAS-3.4.5-GCC-14.3.0.eb"

[boegelbot]

@boegel: 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=3997 EB_ARGS="--installpath /tmp/$USER/pr3997 FlexiBLAS-3.3.1-GCC-12.3.0.eb FlexiBLAS-3.4.5-GCC-14.3.0.eb" EB_CONTAINER= EB_REPO=easybuild-easyblocks EB_BRANCH=develop /opt/software/slurm/bin/sbatch --job-name test_PR_3997 --ntasks="16" ~/boegelbot/eb_from_pr_upload_jsc-zen3.sh' executed!

• exit code: 0
• output:

Submitted batch job 9023

Test results coming soon (I hope)...

- notification for comment with ID 3620701547 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

Overview of tested easyconfigs (in order)

• SUCCESS FlexiBLAS-3.3.1-GCC-12.3.0.eb
• SUCCESS FlexiBLAS-3.4.5-GCC-14.3.0.eb

Build succeeded for 2 out of 2 (total: 17 mins 24 secs) (2 easyconfigs in total)
jsczen3c2.int.jsc-zen3.fz-juelich.de - Linux Rocky Linux 9.6, x86_64, AMD EPYC-Milan Processor (zen3), Python 3.9.21
See https://gist.github.com/boegelbot/fca1c4b610d16d6cef157dd648d53eb7 for a full test report.

[boegel]

lgtm