Prevent potential deadlock if accelerated globals cannot be allocated

Not sure if this is possible to hit in practice, zend_accel_error_noreturn
doesn't return so the unlock isn't called. Other callsites that use both
zend_accel_error_noreturn and zend_shared_alloc_unlock first perform the
unlocking.

Closes phpGH-11718.

Author: nielsdos

NEWS

@@ -48,6 +48,8 @@ PHP                                                                        NEWS
 - Opcache:
   . Fixed bug GH-10914 (OPCache with Enum and Callback functions results in
     segmentation fault). (nielsdos)
+  . Prevent potential deadlock if accelerated globals cannot be allocated.
+    (nielsdos)
 
 - PCNTL:
   . Fixed bug GH-11498 (SIGCHLD is not always returned from proc_open).

ext/opcache/ZendAccelerator.c

@@ -2863,8 +2863,8 @@ static int zend_accel_init_shm(void)
 		accel_shared_globals = zend_shared_alloc(sizeof(zend_accel_shared_globals) + sizeof(uint32_t));
 	}
 	if (!accel_shared_globals) {
-		zend_accel_error_noreturn(ACCEL_LOG_FATAL, "Insufficient shared memory!");
 		zend_shared_alloc_unlock();
+		zend_accel_error_noreturn(ACCEL_LOG_FATAL, "Insufficient shared memory!");
 		return FAILURE;
 	}
 	memset(accel_shared_globals, 0, sizeof(zend_accel_shared_globals));