Add support for generating non-abi3 python import libraries for Windows targets

[messense]

Continuing from PyO3/python3-dll-a#12

[messense]

error[E0432]: unresolved import `python3_dll_a::ImportLibraryGenerator`
 --> /home/runner/work/pyo3/pyo3/pyo3-build-config/src/import_lib.rs:6:5
  |
6 | use python3_dll_a::ImportLibraryGenerator;
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no `ImportLibraryGenerator` in the root

This is odd, I've already patched it to git dependency.

@ravenexp Could you release a new version of python3-dll-a so we can just test with crates.io version? Thanks!

[ravenexp]

@ravenexp Could you release a new version of python3-dll-a so we can just test with crates.io version? Thanks!

Created PyO3/python3-dll-a#16

Edit: v0.2.2 is on crates.io now.

[messense]

Needs PyO3/python3-dll-a#17

[ravenexp]

Needs PyO3/python3-dll-a#17

Mirroring my concerns here because they also affect PyO3 PyO3/python3-dll-a#17 (comment)

[ravenexp]

LGTM

[ravenexp]

I think this is correct, because the other call site gets the mingw flag value from the Python interpreter itself, not from the current Rust compile target, like I did above:

pyo3/pyo3-build-config/src/impl_.rs

Lines 258 to 265 in ea37acb

	let lib_name = if cfg!(windows) {
	default_lib_name_windows(
	version,
	implementation,
	abi3,
	map["mingw"].as_str() == "True",
	)
	} else {

[davidhewitt]

You folks have been doing some really cool stuff here, thanks so much for this!