bug#74217: Bootstrapping Zig with no Binary Blobs

[Hilton Chain <hako@ultrarare.space>]

On Mon, 02 Dec 2024 13:11:53 +0800,
Hilton Chain wrote:
>
> On Thu, 28 Nov 2024 19:08:09 +0800,
> Hilton Chain wrote:
> >
> > Made "#:zig-inputs" a private keyword, its value will be passed to inputs like
> > cargo-build-system (the build system doesn't extract the whole closure for
> > now, this can be added in the future depending on how Zig ecosystem develops).
>
> Just thought if we can avoid using #:zig-inputs, it turns out doing so is quite
> easy:

Added two procedures producing origin snippets in (gnu packages zig-xyz).

'add-build.zig.zon' for generating build.zig.zon, currently unused.
'rename-zig-dependencies' for replacing #:zig-inputs.

I'll try to make unpack-dependencies phase reading dependencies from
build.zig.zon instead of input labels so that we can have more specificity.