Merge pull request #1350 from davidhewitt/refactor-build-rs

Refactor build rs

Author: davidhewitt

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Added
 - Add support for `#[pyclass(dict)]` and `#[pyclass(weakref)]` with the `abi3` feature on Python 3.9 and up. [#1342](https://github.com/PyO3/pyo3/pull/1342)
 - Add FFI definitions `PyOS_BeforeFork`, `PyOS_AfterFork_Parent`, `PyOS_AfterFork_Child` for Python 3.7 and up. [#1348](https://github.com/PyO3/pyo3/pull/1348)
+- Add support for cross-compiling to Windows without needing `PYO3_CROSS_INCLUDE_DIR`. [#1350](https://github.com/PyO3/pyo3/pull/1350)
 
 ### Changed
 - Deprecate FFI definitions `PyEval_CallObjectWithKeywords`, `PyEval_CallObject`, `PyEval_CallFunction`, `PyEval_CallMethod` when building for Python 3.9. [#1338](https://github.com/PyO3/pyo3/pull/1338)