René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Clean up `_ctypes`/`libffi` build, particularly on macOS","articleBody":"bpo-28491/gh-72677 was closed after bpo-41100/gh-85272, but [`Modules/_ctypes/libffi_osx`](https://github.com/python/cpython/tree/3.11/Modules/_ctypes/libffi_osx) wasn't actually removed, just made inaccessible to any build.  In the course of figuring out whether it is in fact unused now, I also stumbled across [`Modules/_ctypes/darwin`](https://github.com/python/cpython/tree/3.11/Modules/_ctypes/darwin), which also appears to be a `dlfcn.h` shim for Mac OS X 10.2 and earlier, and as far as I can tell has been unused for years.  And, of course, with no local copy of `libffi` on any platform anymore, there's no need for `--with-system-ffi` to stick around, which also pointed me towards a needless `-DMACOSX` in the macOS build of `_ctypes`.  I'll be attaching a series of PRs for 3.12 (only) removing all of these, each of which can be done independently.\r\n\r\n\u003c!-- gh-linked-prs --\u003e\r\n### Linked PRs\r\n* gh-100541\r\n* gh-100542\r\n* gh-100543\r\n* gh-100544\r\n\u003c!-- /gh-linked-prs --\u003e\r\n","author":{"url":"https://github.com/zware","@type":"Person","name":"zware"},"datePublished":"2022-12-26T20:49:42.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/100540/cpython/issues/100540"}