Add per-extension child initialization hooks - #24647

The latest revision advances each child RNG state by a PID-derived distance without reseeding or changing the parent state. The reviewer confirmed this should work; all CI checks are green.

Addressed the review by adding macros to declare and reference child-init hooks. Fixed CI build failures by replacing obsolete atomic-store calls in zend_test; checks are rerunning.

Fixed the CI build failures by restoring the missing generated arginfo entries for both zend_test functions. The CI checks are running again.

About the STANDARD_MODULE_PROPERTIES_EX_WITH_CHILD_INIT() macro: It's fine now, but it will not scale if we add more hooks later (I plan to add at least one). I'm wondering if we could use named initializers instead:

• Omit the new field child_init_func from STANDARD_MODULE_PROPERTIES_EX
• Update STANDARD_MODULE_PROPERTIES_EX to use named initializers
• Move the field before the ones initialized by STANDARD_MODULE_PROPERTIES_EX
• Set child_init_func explicitly:

/* We can even omit the zero ones here: */
#define STANDARD_MODULE_PROPERTIES_EX \
    .module_started = 0, \
    .type = 0, \
    .handle = NULL, \
    .module_number = 0, \
    .build_id = ZEND_MODULE_BUILD_ID

struct _zend_module_entry {
	// ...
	zend_result (*post_deactivate_func)(void);
	void (*child_init_func)(void), // the new one
	int module_started;
	unsigned char type;
	void *handle;
	int module_number;
	const char *build_id;
};

zend_module_entry zend_test_module_entry = {
	STANDARD_MODULE_HEADER,
	"zend_test",
	ext_functions,
	PHP_MINIT(zend_test),
	PHP_MSHUTDOWN(zend_test),
	PHP_RINIT(zend_test),
	PHP_RSHUTDOWN(zend_test),
	PHP_MINFO(zend_test),
	PHP_ZEND_TEST_VERSION,
	PHP_MODULE_GLOBALS(zend_test),
	PHP_GINIT(zend_test),
	PHP_GSHUTDOWN(zend_test),
	NULL,
        .child_init_func = PHP_CINIT(zend_test),
	STANDARD_MODULE_PROPERTIES_EX,
};

The mix between named and unnamed is a bit ugly, so extensions that use child_init_func may switch to fully named initializers.

@TimWolla @kairosci thoughts?

I'm wondering if we could use named initializers instead:

I'm a big fan of named initializers. I'm already annoyed when I want to add additional hooks after the fact and need to count which NULL to replace, because of course there is no comment either 😅

@arnaud-lb @TimWolla I updated to use named initializers. The field name makes the callback’s purpose clear, so no comment is needed.

Thank you @kairosci. Please resolve #24647 (comment) and then we are good to merge. Also please rebase and re-run build/gen_stubs.php to resolve the conflicts.

@TimWolla @arnaud-lb I think I've addressed all the reviews and conflicts.
Sorry again for missing some of them earlier!
Let me know if there's anything else I overlooked.

Thank you!