remove boost as mandatory dependency

[psychocoderHPC]

fix #481

Make boost an optional dependency.
alpaka::core::demangled<TYPE> returns a mangled name in case boost is not available. #2405 can solve this but should not be mixed into this PR.
This PR removes the mixing of alpakas own defines e.g BOOST_LANG_HIP which looked like boost but was exposed by alpaka under BOOST names.

This PR is a base for discussion at the next developer meeting. In a separate PR we could reduce the number of tested boost versions. We should also run tests without boost at all.

[SimeonEhrig]

@psychocoderHPC Can you please split up the PR. At least in two PR: remove boost::atomic_ref and the compiler detection.

At the moment it is nearly impossible to review it and I also saw, that you didn't modify the CI, which is definitively useful.

[SimeonEhrig]

I think also a third PR with the demangling function names is useful.

[psychocoderHPC]

Yes, I can do this after we discuss it in general.

[SimeonEhrig]

Yes, I can do this after we discuss it in general.

You got me. I didn't read the description until the end 😬

[SimeonEhrig]

@psychocoderHPC Can you please short summarize the main changes?

If I'm not wrong the following boost features are used:

• preprocessor defines for compiler detection
• boost::atomic_ref if std::atomic_ref is not avaible
• demangle type names

Did I missed something?

[psychocoderHPC]

@psychocoderHPC Can you please short summarize the main changes?

If I'm not wrong the following boost features are used:

• preprocessor defines for compiler detection
• boost::atomic_ref if std::atomic_ref is not avaible
• demangle type names

Did I missed something?

no thats a good summery