[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.