Update config for coroutines on ARM

[hkaiser]

@eugeneswalker would you be able to try #38812? This is a missing conflict in the package. @hkaiser I think you can also update the ifdefs in HPX to fall back to the posix implementation as an alternative to Boost.Context. If and when you update those in HPX we can add an upper bound for the version in the conflict.

Originally posted by @msimberg in spack/spack#38796 (comment)

[hkaiser]

This has been fixed.

[felixguendling]

Are there plans to officially support ARM officially as a platform? As ARM became more and more relevant in all areas, including servers/cloud, this would make hpx more interesting.

The documentation does not list ARM as supported:
https://github.com/STEllAR-GROUP/hpx/blob/master/docs/sphinx/manual/prerequisites.rst?plain=1#L20-L29

[hkaiser]

Are there plans to officially support ARM officially as a platform? As ARM became more and more relevant in all areas, including servers/cloud, this would make hpx more interesting.

The documentation does not list ARM as supported: https://github.com/STEllAR-GROUP/hpx/blob/master/docs/sphinx/manual/prerequisites.rst?plain=1#L20-L29

Right, we should add ARM and RISC-V to the officially supported platforms. @felixguendling even if the docs don't say so explicitly, HPX master does support both platforms.

@dimitraka could you please take of this?