Archdetect riscv update

[hugomeiland]

This update will treat the isa line from a riscv cpu (e.g. rv64imafdcv_zicbom_zicboz_zicntr_zicond_zicsr_zifencei_zihintpause_zihpm_zfh_zfhmin_zca_zcd_zba_zbb_zbc_zbs_zkt_zve32f_zve32x_zve64d_zve64f_zve64x_zvfh_zvfhmin_zvkt_sscofpmf_sstc_svinval_svnapot_svpbmt) and sed it into seperate flags which can be matched as relevant (!) features, the same way we do for x86_64. This should allow cpu's with the same relevant features, but from different vendors to be matched to the same cpu paths.

[julianmorillo]

I think this update makes sense as it certainly gives more flexibility and would allow working with subsets of extensions instead of matching the whole ISA string. I suggest to change the comment in eessi_archdetect.sh to something like:

# RISC-V ISA strings use '_' as extension separators.
# Convert them to space-separated feature tokens so they
# can be matched like x86 CPU flags.

as it explains better why the replacement is done. The tokens here are just features/extensions and do not translate to compilation flags (in contrast with x86). At the end, when building we will need the ISA string (with underscores) anyway to pass it to the -march option.

Which makes me think... if we do:

bot: build repo:dev.eessi.io-riscv-2025.06-001 instance:eessi-bot-riscv for:arch=riscv64/sifive/p550

where/how is the ISA string to pass to -march determined? Doesn't it directly come from init/arch_specs/eessi_arch_riscv.spec ? I think this would require an update at some other script...

[riscv-eessi-io-bot]

New job on instance eessi-bot-riscv for repository dev.eessi.io-riscv-2025.06-001
Building on: sifive-p550
Building for: riscv64/sifive/p550
Job dir: /home/eessibot/shared/jobs/2026.06/pr_243/309668

date	job status	comment
Jun 03 13:06:42 UTC 2026	submitted	job id 309668 awaits release by job manager
Jun 03 13:07:07 UTC 2026	released	job awaits launch by Slurm scheduler
Jun 03 13:08:15 UTC 2026	running	job 309668 is running
Jun 03 13:09:22 UTC 2026	finished	🤷 UNKNOWN (click triangle for detailed information) Job results file _bot_job309668.result does not exist in job directory, or parsing it failed. No artefacts were found/reported.
Jun 03 13:09:22 UTC 2026	test result	🤷 UNKNOWN (click triangle for detailed information) Job test file _bot_job309668.test does not exist in job directory, or parsing it failed.