Required files missing from combined source tarball

[SED4906]

When building from the released glide.source.tar.zst, mach configure/mach build fail due to some files not being present. In particular:

• .cargo/config.toml.in: contains information for vendored Rust dependencies. The tarball contains the vendored dependencies as expected, but this file is needed to tell Cargo it should use them; configure fails if it doesn't exist or have any useful contents, build fails if the contents are wrong.
• .ycm_extra_conf.py: I'm not sure if/how this is even used during mach build, but configure fails if it doesn't exist.

[RobertCraigie]

Thanks for the report! This should be fixed in the next release. 4483d8f