* mingw64 platform string is like mingw_xxx not "mingw"
See https://github.com/msys2/MINGW-packages/blob/master/mingw-w64-python/0099-Change-the-get_platform-method-in-sysconfig-and-dist.patch
* Mingw: Do not dllexport exceptions
This is a fix for errors like:
D:/a/pybind11/pybind11/include/pybind11/detail/common.h:735:23: error: 'dllexport' implies default visibility, but 'class pybind11::builtin_exception' has already been declared with a different visibility
735 | class PYBIND11_EXPORT builtin_exception : public std::runtime_error {
| ^~~~~~~~~~~~~~~~~
* GHA: Test Mingw64 build
* fix: avoid thin binaries on mingw
* fix: drop lto on MinGW
* Mingw64: disable PYBIND11_DEPRECATED
It trigger many warnings for unknown reasons
Co-authored-by: Henry Schreiner <henryschreineriii@gmail.com>