[GIT-PULLS] [php-src] PR #22956: ext/sysvmsg: fix IPC_PRIVATE and out-of-range key handling

Pull Request: https://github.com/php/php-src/pull/22956
Author: iliaal

msgget() has no size argument to fail on, so unlike shmget() it always creates when handed IPC_PRIVATE. `msg_queue_exists(0)` creates a queue with mode 0000, throws away the id and returns true; the same probe in `msg_get_queue()` succeeds, so the create call never runs and the returned object wraps a queue with no permission bits.

```php
var_dump(msg_queue_exists(0));  // true, one queue leaked per call
$q = msg_get_queue(0, 0600);
var_dump(msg_stat_queue($q));   // false: mode is 0000, not 0600
```

Both now skip the probe for IPC_PRIVATE. msg_queue_exists() returns false, since no queue is ever addressable by that key, and msg_get_queue() goes straight to msgget(key, IPC_CREAT | IPC_EXCL | perms).

The out-of-range key check mirrors GH-9945, which landed for shmop_open() and shm_attach() in 34116adc119 and was never applied here. sysvmsg still passed a zend_long to msgget(), so 0x100000000 truncates to key_t 0 and creates a queue the same way.

Noticed while reviewing php/php-src#22912, where two of the test workarounds exist because of this.