add custom easyblock for AOCC

[SebastianAchilles]

(created using eb --new-pr)

EasyBlock for AOCC:

• uses check_accepted_eula from add support for --accept-eula configuration option + 'accept_eula' easyconfig parameter easybuild-framework#3535
• the sanity_check_step is based on https://github.com/easybuilders/easybuild-easyblocks/blob/develop/easybuild/easyblocks/c/clang.py as AOCC is based on Clang
• sets custom environment variables

Some of the paths in the sanity_check depend on the version of Clang that AOCC is based on. I have added a custom parameter clangversion. If this is not set in the easyconfig, it tries to find the clangverison in the mapping from AOCC version to Clang version map_aocc_to_clang_ver which is hardcoded in the EasyBlock. I am not sure if that is the best solution. An alternative would either be to remove the check for the paths that contain clangversion, or use an wildcard (is this possible?).

Can be tested with easybuilders/easybuild-easyconfigs#11868

[boegel]

Small additional code style suggestion: we often use single quotes for string values that don't have spaces, and double quotes for string values that do have spaces.

You're doing it exactly reversed in sanity_check_step, which throws me off a bit.

We don't strictly enforce this, but if you're up for it, please change...

[boegel]

Tested with easybuilders/easybuild-easyconfigs#11868, works like a charm, thanks @SebastianAchilles!