[php-src] PR #24042: TSRM: Fix Windows shared memory payload offset

Pull Request: https://github.com/php/php-src/pull/24042 Author: iliaal On Windows, shmat() returned shm->descriptor + sizeof(shm->descriptor), which is pointer arithmetic on a struct shmid_ds pointer, so the payload began 448 bytes into the view on x64 while shmget() had reserved only 8 bytes for the 56-byte descriptor and reported that inflated size in shm_segsz. A shmop or sysvshm segment whose end lies near a page boundary therefore faults on write, and shmop_size() over-reports by 8 bytes. This dates back to d7bdc040b4e (PHP 8.2), which moved the descriptor into the payload mapping. The payload now starts right after one descriptor, the mapping reserves sizeof(struct shmid_ds), and shm_segsz holds the requested size.