Namespaced types: fix build for 17.0

[matwey]

No description provided.

[ghost]

Thanks @matwey.

We need to define the same macro in the bootstrap escript, too. Also, we should add a comment in rebar.config and bootstrap explaining when (>= 17.x) and why (compiler warning) namespaced_types is defined. For future reference it'd be best to include a sample warning message in both comments.

That said, assuming we want to keep the type specs, this seems like a practical solution.

[ghost]

Thanks for the fixes.

How about using a different comment?

Problem:
Beginning with Erlang 17.0 the compiler emits the following warning:
type dict/0 is deprecated and will be removed in OTP 18.0;
use use dict:dict/0 or preferably dict:dict/2
Solution:
When building on >= 17.x we define namespaced_types and use it as a
condition whether to fully qualify built-in types (dict:dict/0 vs dict/0).

The comment should also be included in both rebar.config and bootstrap where namespaced_types is defined.

[matwey]

I've added the comments.