Incorrect patch stub format causes dh-cargo-vendored-sources to fail

[Max Gilmour]

Starting in rustc-1.89, cargo-vendor-filterer was used to automatically generate crate stubs for unwanted vendored dependencies.

However, dh-cargo-vendored-sources checks for an empty src/lib.rs to determine whether or not a given crate is a stub, and the patch used to generate the crate stubs contains a single newline, making dh-cargo-vendored-sources erroneously believe these crates were indeed included in the source.

[Max Gilmour (maxgmr)]

This is the first of the two new tarballs. It contains all upstream code except vendored dependencies.

[Max Gilmour (maxgmr)]

This is the second of the two new orig tarballs. This tarball component contains the pruned vendored dependencies.

[Max Gilmour (maxgmr)]

I would be very grateful if someone could sponsor this fix. The new tarballs can be found in my previous comments.

This patch fixes LP: #2132631, an issue where the incorrect formatting of stubbed vendored dependencies caused the list of vendored sources to be incorrect, thus potentially causing problems down the line for automated dependency checkers.

===============
Notable Changes
===============
- The d/prune-unused-deps overhaul has been reversed, as it is no longer used to generate patch stubs.
- d/vendor-deps has been added, and d/rules edited, to implement the vendor-tarball rule. This allows the maintainer to generate the pruned vendored dependencies as a tarball component.
- d/p/series,d/p/prune/d-0021-vendor-remove-windows-dependencies.patch: This very large patch, which generated the vendored crate stubs, has been removed entirely as it is no longer necessary.
- d/add-vendored-copyright-overrides has been added as a way to conveniently override Lintian warnings for missing copyright stanzas of empty vendored crate stubs.
- The obsolete autogenerated vendor Files-Excluded list has been removed from d/copyright.

The vast majority of this debdiff is taken up by the newly-generated vendored dependency stubs. They aren't anything new, they're just included in the orig tarball rather than being generated on-the-fly via a patch.

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Links
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PPA: https://launchpad.net/~maxgmr/+archive/ubuntu/rustc-1.89-lp2132631/+packages
Source: https://git.launchpad.net/~canonical-foundations/ubuntu/+source/rustc/log/?h=merge-1.89
amd64 Autopkgtests: https://autopkgtest.ubuntu.com/results/autopkgtest-resolute-maxgmr-rustc-1.89-lp2132631/resolute/amd64/r/rustc-1.89/20251202_230803_1df8a@/log.gz