[boost] [hash][array][stacktrace][type_index] Adding noexcept to hash

Hi, I want to add noexcept support to the hash library, but a few libraries (array, stacktrace, type_index, maybe more) forward declare hash_range for themselves, causing errors if I add a noexpect specifier to hash_range. If I move hash_fwd.hpp into the core module, so that it doesn't add a dependency on the functional module, would they be okay with including it from there? thanks, Daniel