Fix Phar::offsetGet() return type

It's possible to change the returned type using setFileClass(),
which unfortunately only enforces that it's a subtype of
SplFileInfo, not PharFileInfo.

Author: nikic

ext/phar/phar_object.stub.php

@@ -106,7 +106,7 @@ public function offsetExists($localName): bool {}
      * @param string $localName
      * @tentative-return-type
      */
-    public function offsetGet($localName): PharFileInfo {}
+    public function offsetGet($localName): SplFileInfo {}
 
     /**
      * @param string $localName
@@ -371,7 +371,7 @@ public function offsetExists($localName): bool {}
      * @tentative-return-type
      * @implementation-alias Phar::offsetGet
      */
-    public function offsetGet($localName): PharFileInfo {}
+    public function offsetGet($localName): SplFileInfo {}
 
     /**
      * @param string $localName

ext/phar/phar_object_arginfo.h

@@ -1,5 +1,5 @@
 /* This is a generated file, edit the .stub.php file instead.
- * Stub hash: fa11774e0b29ff4f711f1677b395545334e1aee9 */
+ * Stub hash: ac04a4161a11d054922cb04787f81f5661203e3e */
 
 ZEND_BEGIN_ARG_INFO_EX(arginfo_class_Phar___construct, 0, 0, 1)
 	ZEND_ARG_TYPE_INFO(0, filename, IS_STRING, 0)
@@ -119,7 +119,7 @@ ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_Phar_offsetExist
 	ZEND_ARG_INFO(0, localName)
 ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_OBJ_INFO_EX(arginfo_class_Phar_offsetGet, 0, 1, PharFileInfo, 0)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_OBJ_INFO_EX(arginfo_class_Phar_offsetGet, 0, 1, SplFileInfo, 0)
 	ZEND_ARG_INFO(0, localName)
 ZEND_END_ARG_INFO()