sip RFE: support prepare_metadata_for_build_wheel hook

[Scott Talbert]

On Tue, 27 Jul 2021, Phil Thompson wrote:

>> I would like to request that sip support the PEP-517 hook
>> prepare_metadata_for_build_wheel.  It appears that sip already has a
>> function for generating the .dist-info so this doesn't seem like it
>> would be too bad?
>
> It would require major refactoring as the creation of .dist-info is an 
> integral part of a build.
>
> Given the hook is optional, and the PEP states how a front end should handle 
> its omission, what would be the motivation?

The motivation is to get the package metadata (e.g., install requirements) 
without having to build it (ie, the wheel) first.

Scott