Immutable clases and op_arrays.

Squashed commit of the following:

commit cd0c36c3f943849e5b97a8dbe2dd029fbeab3df9
Merge: 4740dabb84 ad6738e886
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Wed Oct 17 14:43:38 2018 +0300

    Merge branch 'master' into immutable

    * master:
      Remove the "auto" encoding
      Fixed bug #77025
      Add vtbls for EUC-TW encoding

commit 4740dabb843c6d4f7f866b4a2456073c9eaf4c77
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Wed Oct 17 14:12:28 2018 +0300

    Reverted back ce->iterator_funcs_ptr. Initialize ce->iterator_funcs_ptr fields in immutable classes.

commit ad7a78b253be970db70c2251e66f9297d8e7f829
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Wed Oct 17 11:46:30 2018 +0300

    Added comment

commit 0276ea51875bab37be01a4dc5e5a047c5698c571
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Wed Oct 17 11:42:43 2018 +0300

    Added type cast

commit c63fc5d5f19c58498108d1698055b2b442227eb3
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Wed Oct 17 11:36:51 2018 +0300

    Moved static class members initialization into the proper place.

commit b945548e9306b1826c881918858b5e5aa3eb3002
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Wed Oct 17 11:21:03 2018 +0300

    Removed redundand assertion

commit d5a41088401814c829847db212488f8aae39bcd2
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Wed Oct 17 11:19:13 2018 +0300

    Removed duplicate code

commit 8dadca8864e66de70a24bdf1181bcf7dd8fb27d7
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Wed Oct 17 11:05:43 2018 +0300

    Hide offset encoding magic in ZEND_MAP_PTR_IS_OFFSET(), ZEND_MAP_PTR_OFFSET2PTR() and ZEND_MAP_PTR_PTR2OFFSET() macros.

commit 9ef07c88bd76801e2d4fbfeab3ebfd6e6a67ac5f
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Wed Oct 17 10:48:29 2018 +0300

    typo

commit a06f0f3d3aba53e766046221ee44fb9720389ecc
Merge: 94099586ec 3412345ffe
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Wed Oct 17 10:47:07 2018 +0300

    Merge branch 'master' into immutable

    * master:
      Remove unused variable makefile_am_files
      Classify object handlers are required/optional
      Add support for getting SKIP_TAGSTART and SKIP_WHITE options
      Remove some obsolete config_vars.mk occurrences
      Remove bsd_converted from .gitignore
      Remove configuration parser and scanners ignores
      Remove obsolete buildconf.stamp from .gitignore
      [ci skip] Add magicdata.patch exception to .gitignore
      Remove outdated ext/spl/examples items from .gitignore
      Remove unused test.inc in ext/iconv/tests

commit 94099586ec599117581ca01c15b1f6c5f749e23a
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Mon Oct 15 23:34:01 2018 +0300

    Immutable clases and op_arrays

1 files changed, 15 insertions, 0 deletions

diff --git a/UPGRADING.INTERNALS b/UPGRADING.INTERNALS
index 132a2d97a7..8f4046032b 100644
--- a/UPGRADING.INTERNALS
+++ b/UPGRADING.INTERNALS
@@ -8,6 +8,7 @@ PHP 7.4 INTERNALS UPGRADE NOTES
   e. php_win32_error_to_msg() memory management
   f. get_properties_for() handler / Z_OBJDEBUG_P
   g. Required object handlers
+  h. Immutable classes and op_arrays
 
 2. Build system changes
   a. Abstract
@@ -121,6 +122,20 @@ PHP 7.4 INTERNALS UPGRADE NOTES
      It is recommended to initialize object handler structures by copying the
      std object handlers and only overwriting those you want to change.
 
+  h. Opcache may make classes and op_arrays immutable. Such classes are marked
+     by ZEND_ACC_IMMUTABLE flag, they are not going to be copied from opcache
+     shared memory to process memory and must not be modified at all.
+     Few related data structures were changed to allow addressing mutable data
+     structures from immutable ones. This access is implemented through
+     ZEND_MAP_PTR... abstraction macros and, basically, uses additional level of
+     indirection. op_array->run_time_cache, op_array->static_variables_ptr and
+     class_entry->static_members_table now have to be accessed through
+     ZEND_MAP_PTR... macros.
+     It's also not allowed to change op_array->reserved[] handles of immutable
+     op_arrays. Instead, now you have to reserve op_array handle using
+     zend_get_op_array_extension_handle() during MINIT and access its value
+     using ZEND_OP_ARRAY_EXTENSION(op_array, handle).
+
 ========================
 2. Build system changes
 ========================