Make weak ref notify robust against bailout

First drop it from EG(weakrefs), as the weakref_unref operation
may call a destructor, which may bail out.

Fixes oss-fuzz #39718.

Zend/tests/weakrefs/weakmap_dtor_exception.phpt

@@ -0,0 +1,18 @@
+--TEST--
+Exception during WeakMap destruction during shutdown
+--FILE--
+<?php
+$map = new WeakMap;
+$obj = new stdClass;
+$map[$obj] = new class {
+    function __destruct() {
+        throw new Exception("Test");
+    }
+};
+?>
+--EXPECTF--
+Fatal error: Uncaught Exception: Test in %s:%d
+Stack trace:
+#0 [internal function]: class@anonymous->__destruct()
+#1 {main}
+  thrown in %s on line %d

Zend/zend_weakrefs.c

@@ -157,8 +157,8 @@ void zend_weakrefs_notify(zend_object *object) {
 	ZEND_ASSERT(tagged_ptr && "Tracking of the IS_OBJ_WEAKLY_REFERENCE flag should be precise");
 #endif
 	if (tagged_ptr) {
-		zend_weakref_unref(obj_addr, tagged_ptr);
 		zend_hash_index_del(&EG(weakrefs), obj_addr);
+		zend_weakref_unref(obj_addr, tagged_ptr);
 	}
 }