feat: add support for building iOS wheels. (#2286)

* Add support for building iOS wheels.

* Replace use of system() in test binary module.

* Restored the 'minimal' approach of the minimal examples.

* Split out platform details into standalone pages, and expand iOS platform details.

* More doc corrections.

* Bump support package to include fix for python/cpython#130292

* Ensure iOS tests are all run on the same xdist worker.

* More iOS documentation tweaks.

* Factor out common xcode version test utility.

* Simplify iOS to a single platform with an expanded interpretation of arch.

* I guess I should update the iOS tests as well...

* Additional safety for missing iOS test output.

* Remove DYLD_LIBRARY_PATH from the iOS environment.

* Make test-sources mandatory for iOS builds.

* Updates and clarifications to documentation.

* Clarify what a slice is.

* Normalize use of underscores in platform name.

* Modify auto target to be matching CPU only.

* Use consistent ordering of platforms in examples.

* Use consistent naming in iOS archiectures.

* Placate the linter.

* Miscellaneous cleanups picked up by @joerick's review.

* Correct the list of expected wheels.

* Correct which 'native' we're actually checking.

* Correct the docs links so they're all relative.

* Correct the identification of free threaded builds.

* Use target instead of host to describe the platform we're building for.

* Rework iOS test to remove issue with log completeness.

* Convert errors to FatalError

Co-authored-by: Matthieu Darbois <mayeut@users.noreply.github.com>
Co-authored-by: Joe Rickerby <joerick@mac.com>

* Removed a repeated check for a valid python.

* Update bin/update_pythons.py to update iOS support packages.

* Document that iOS CI is available on other platforms.

* Restore a comment needed for some platforms.

* Small cleanups identified in code review

Co-authored-by: Joe Rickerby <joerick@mac.com>

* Simplify logic to appease linter.

* Modify dependency constraint handling to use new API.

* Cosmetic change to trigger a CI rebuild.

---------

Co-authored-by: Matthieu Darbois <mayeut@users.noreply.github.com>
Co-authored-by: Joe Rickerby <joerick@mac.com>

test/test_projects/c.py

@@ -8,15 +8,16 @@ SPAM_C_TEMPLATE = r"""
 {{ spam_c_top_level_add }}
 
 static PyObject *
-spam_system(PyObject *self, PyObject *args)
+spam_filter(PyObject *self, PyObject *args)
 {
-    const char *command;
+    const char *content;
     int sts;
 
-    if (!PyArg_ParseTuple(args, "s", &command))
+    if (!PyArg_ParseTuple(args, "s", &content))
         return NULL;
 
-    sts = system(command);
+    // Spam should not be allowed through the filter.
+    sts = strcmp(content, "spam");
 
     {{ spam_c_function_add | indent(4) }}
 
@@ -25,7 +26,7 @@ spam_system(PyObject *self, PyObject *args)
 
 /* Module initialization */
 static PyMethodDef module_methods[] = {
-    {"system", (PyCFunction)spam_system, METH_VARARGS,
+    {"filter", (PyCFunction)spam_filter, METH_VARARGS,
      "Execute a shell command."},
     {NULL}  /* Sentinel */
 };