Rollup merge of rust-lang#118445 - ferrocene:jp-support-reuse-in-submodules, r=Mark-Simulacrum

Let `reuse` look inside git submodules

Changes `collect-license-metadata` and `generate-copyright` so they can now look at the git submodules.

Unfortunately `reuse` chokes on the LLVM submodule - it finds the word "Copyright" or the unicode copyright symbol in all kinds of places, including UTF-8 test cases. The `reuse` tool expressly won't let you ignore folders, so we let it scan everything and then strip out the LLVM sub-folder in post. Instead, we add in a hand-curated list of copyright information gleaned by reading the LLVM codebase carefully, which is stored in `.reuse/dep5` in Debian format where `reuse` can find and use it.

The `.reuse/dep5` continues to track copyright info for files in the tree that do not have SPDX metadata in them (i.e. all of them)

Author: matthiaskrgr

crates/stdx/src/anymap.rs

@@ -1,5 +1,6 @@
 //! This file is a port of only the necessary features from https://github.com/chris-morgan/anymap version 1.0.0-beta.2 for use within rust-analyzer.
-//! Copyright © 2014–2022 Chris Morgan. COPYING: https://github.com/chris-morgan/anymap/blob/master/COPYING"
+//! Copyright © 2014–2022 Chris Morgan.
+//! COPYING: https://github.com/chris-morgan/anymap/blob/master/COPYING
 //! Note that the license is changed from Blue Oak Model 1.0.0 or MIT or Apache-2.0 to MIT OR Apache-2.0
 //!
 //! This implementation provides a safe and convenient store for one value of each type.