Vendor things

third-party/vendor/stacker/README.md

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+# stacker
+
+[![Build Status](https://github.com/rust-lang/stacker/workflows/Test%20stacker/badge.svg)](https://github.com/rust-lang/stacker/actions)
+
+[Documentation](https://docs.rs/stacker)
+
+A stack-growth library for Rust. Enables annotating fixed points in programs
+where the stack may want to grow larger. Spills over to the heap if the stack
+has hit its limit.
+
+This library is intended on helping implement recursive algorithms.
+
+```toml
+# Cargo.toml
+[dependencies]
+stacker = "0.1"
+```
+
+## Platform Support
+
+This library currently uses psm for its cross platform capabilities, with a notable exception of
+Windows, which uses an implementation based on Fibers. See the README for psm for the support
+table.
+
+On all unsupported platforms this library is a noop. It should compile and run, but it
+won't actually grow the stack and code will continue to hit the guard pages
+typically in place.
+
+# License
+
+This project is licensed under either of
+
+ * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
+   https://www.apache.org/licenses/LICENSE-2.0)
+ * MIT license ([LICENSE-MIT](LICENSE-MIT) or
+   https://opensource.org/licenses/MIT)
+
+at your option.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in this project by you, as defined in the Apache-2.0 license,
+shall be dual licensed as above, without any additional terms or conditions.