Added readonly reinitable helper

[NickSdot]

Follow up to #22654 as discussed in #22588 (comment).

Added zend_object_set_properties_reinitable() to centralise temporarily allowing reinitialisation of initialised readonly properties during controlled operations such as cloning and unserialisation.

cc @TimWolla

[github-actions]

AWS x86_64 (c6id.metal)

Attribute	Value
Environment	aws
Instance type	c6id.metal
Architecture	x86_64
CPU	Intel(R) Xeon(R) Platinum 8375C CPU @ 2.90GHz, 64 cores @ 2900 MHz
CPU settings	disabled deeper C-states, disabled turbo boost, disabled hyper-threading
RAM	251 GB
Kernel	6.18.20-20.229.amzn2023.x86_64
OS	Amazon Linux 2023.11.20260427
GCC	14.2.1
Time	2026-07-19 12:47:00 UTC
Job details	https://github.com/php/php-src/actions/runs/29687603092 (Artifacts)
Changeset	https://github.com/php/php-src/compare/3129b3baab..41991abf62

Laravel 12.11.0 demo app - 50 iterations, 50 warmups, 100 requests (sec)

PHP	Min	Max	Std dev	Rel std dev %	Mean	Mean diff %	Median	Median diff %	Skewness	Z-stat	P-value	Memory
PHP - baseline@3129b3b	0.38958	0.39160	0.00038	0.10%	0.38999	0.00%	0.38991	0.00%	2.192	0.000	1.000	25.78 MB
PHP - baseline@3129b3b (JIT)	0.36355	0.36684	0.00088	0.24%	0.36455	-6.52%	0.36422	-6.59%	1.356	8.614	0.000	25.73 MB
PHP - readonly-reinitable-helper	0.39001	0.39162	0.00040	0.10%	0.39052	0.14%	0.39041	0.13%	1.175	-6.594	0.000	25.78 MB
PHP - readonly-reinitable-helper (JIT)	0.36336	0.36740	0.00095	0.26%	0.36468	-6.49%	0.36433	-6.56%	0.908	8.614	0.000	25.73 MB

Symfony 2.8.0 demo app - 50 iterations, 50 warmups, 100 requests (sec)

PHP	Min	Max	Std dev	Rel std dev %	Mean	Mean diff %	Median	Median diff %	Skewness	Z-stat	P-value	Memory
PHP - baseline@3129b3b	0.67113	0.67315	0.00045	0.07%	0.67165	0.00%	0.67151	0.00%	1.792	0.000	1.000	25.75 MB
PHP - baseline@3129b3b (JIT)	0.64124	0.65052	0.00153	0.24%	0.64210	-4.40%	0.64165	-4.45%	4.318	8.614	0.000	26.20 MB
PHP - readonly-reinitable-helper	0.67079	0.67449	0.00059	0.09%	0.67163	-0.00%	0.67151	0.00%	2.728	0.531	0.596	26.14 MB
PHP - readonly-reinitable-helper (JIT)	0.64025	0.64479	0.00071	0.11%	0.64087	-4.58%	0.64072	-4.58%	3.823	8.614	0.000	26.20 MB

Wordpress 6.9 main page - 50 iterations, 20 warmups, 20 requests (sec)

PHP	Min	Max	Std dev	Rel std dev %	Mean	Mean diff %	Median	Median diff %	Skewness	Z-stat	P-value	Memory
PHP - baseline@3129b3b	0.58768	0.59215	0.00065	0.11%	0.58823	0.00%	0.58811	0.00%	4.634	0.000	1.000	26.21 MB
PHP - baseline@3129b3b (JIT)	0.51871	0.52291	0.00113	0.22%	0.51980	-11.63%	0.51944	-11.68%	1.609	8.614	0.000	26.29 MB
PHP - readonly-reinitable-helper	0.58739	0.59227	0.00073	0.12%	0.58823	-0.00%	0.58810	-0.00%	3.830	0.489	0.625	26.16 MB
PHP - readonly-reinitable-helper (JIT)	0.51864	0.52319	0.00078	0.15%	0.51937	-11.71%	0.51923	-11.71%	3.373	8.614	0.000	26.29 MB

bench.php - 50 iterations, 20 warmups, 2 requests (sec)

PHP	Min	Max	Std dev	Rel std dev %	Mean	Mean diff %	Median	Median diff %	Skewness	Z-stat	P-value	Memory
PHP - baseline@3129b3b	0.44963	0.45162	0.00052	0.12%	0.45069	0.00%	0.45074	0.00%	-0.231	0.000	1.000	26.22 MB
PHP - baseline@3129b3b (JIT)	0.14419	0.14498	0.00017	0.11%	0.14461	-67.91%	0.14464	-67.91%	-0.141	8.614	0.000	26.30 MB
PHP - readonly-reinitable-helper	0.44972	0.45338	0.00068	0.15%	0.45113	0.10%	0.45116	0.09%	0.509	-3.392	0.001	26.18 MB
PHP - readonly-reinitable-helper (JIT)	0.14426	0.14513	0.00021	0.15%	0.14466	-67.90%	0.14465	-67.91%	0.447	8.614	0.000	26.30 MB