Export SUPPORTS_SHARED_LIBRARIES in ocamlc -config

[dra27]

Exposes SUPPORTS_SHARED_LIBRARIES from Makefile.config as shared_libraries in ocamlc -config

[gasche]

I support the feature and believe the implementation is correct. Do we get five minutes to discuss whether supports_shared_libraries isn't a more descriptive name (in term of suggesting booleanness) than shared_libraries?

(supports_shared_libraries is what ocamlbuild's ocamlbuild_config.ml uses, but I think there the idea was just to directly reuse the upstream name rather than any conscious naming decision.)

[dra27]

I um'd and ah'd over the name (it has two names in our code base too - it's different in s.h!). I'm not attached to the name at all, although other booleans (e.g. windows_unicode, flamda) have similarly non-Boolean names.

I'm in no particular rush for this to be merged, so happy to wait for other additional (!) opinions on suitable naming.

[mshinwell]

I tend to think it would be better to keep this patch consistent as regards naming, so the config dump should be "supports_shared_libraries". @dra27 Can you make this change and then merge?

[gasche]

(independently of the naming discussion, here is a magical seal of approval.)

[dra27]

@mshinwell - (finally) done. I'll merge when CI passes.