--pre was not necessary to install google-protobuf when I tried it today (2017-12-06).

* Reserve unknown in ruby

* Revert ruby tests. Wait for cpp impl for conformance test

* Add conformance test for preserving unknown

* Add unknown field conformance test to csharp failure list.

* Fix comments

* Fix comment

* Fix comments

* Fix typo

* Use stringsink_string directly

* Mark hd unused

* Remove unused encodeunknown_handlerfunc

* Fix ruby segment fault

1) rb_ary_new cannot be called during allocate function. During allocate
fucntion, the containing object hasn't been marked and rb_ary_new may
invoke gc to collect containing object.
2) The global map should be marked before allocating it. Otherwise it
may be garbage collected.

* Add test

* Remove commented code

* Fix grammer error

This makes the frame stack per-parser, and per-thread.  Fixes #3250

This makes the frame stack per-parser, and per-thread.  Fixes #3250

* Fixed a bunch of Ruby conformance errors.

* Fixed some more Ruby conformance errors in JSON.

`.quo` return the most exact devision which fixes accuracy problems for the
timestamp coercion

We have some special code in wrap_memcpy.c to ensure that we use the
2.2.5 version of memcpy, for compatibility with older versions of glibc.
However, we need to make sure we only attempt to do this when we are
actually building with glibc, so that the code can also build
successfully against other libc implementations such as musl.

Usage: Message.encode_json(m, emit_defaults: true)
Message fields that are nil will still not appear in the encoded JSON.

This commit adds a __wrap_memcpy function and a linker flag to use that
in place of memcpy for our Ruby gem C extension. This allows us to
always use the 2.2.5 version of memcpy, making it possible to use the
gem on distributions with pre-2.14 versions of glibc.

Before this change:
$ objdump -T protobuf_c.so | grep memcpy
0000000000000000      DF *UND*  0000000000000000  GLIBC_2.3.4 __memcpy_chk
0000000000000000      DF *UND*  0000000000000000  GLIBC_2.14  memcpy

After:
$ objdump -T protobuf_c.so | grep memcpy
0000000000000000      DF *UND*  0000000000000000  GLIBC_2.2.5 memcpy
0000000000000000      DF *UND*  0000000000000000  GLIBC_2.3.4 __memcpy_chk
0000000000042450 g    DF .text  0000000000000005  Base __wrap_memcpy

This is based on gRPC's solution to a similar problem:
https://github.com/grpc/grpc/blob/5098508d2d41a116113f7e333c516cd9ef34a943/src/core/lib/support/wrap_memcpy.c

This fixes issue #2783.

The first is the newer name, which is also more telling.

The "New BSD License" is the "3-Clause BSD License", but the links were
pointing to the "2-Clause BSD License".

* Down-integrate internal changes to github.

* Update conformance test failure list.

* Explicitly import used class in nano test to avoid random test fail.

* Update _GNUC_VER to use the correct implementation of atomic operation
on Mac.

* maps_test.js: check whether Symbol is defined before using it (#2524)

Symbol is not yet available on older versions of Node.js and so this
test fails with them. This change just directly checks whether Symbol is
available before we try to use it.

* Added well_known_types_embed.cc to CLEANFILES so that it gets cleaned up

* Updated Makefile.am to fix out-of-tree builds

* Added Bazel genrule for generating well_known_types_embed.cc

In pull request #2517 I made this change for the CMake and autotools
builds but forgot to do it for the Bazel build.

* Update _GNUC_VER to use the correct implementation of atomic operation on Mac.

* Add new js file in extra dist.

* Bump version number to 3.2.0

* Fixed issue with autoloading - Invalid paths (#2538)

* PHP fix int64 decoding (#2516)

* fix int64 decoding

* fix int64 decoding + tests

* Fix int64 decoding on 32-bit machines.

* Fix warning in compiler/js/embed.cc

embed.cc: In function ‘std::string CEscape(const string&)’:
embed.cc:51:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < str.size(); ++i) {
                                ^

* Fix include in auto-generated well_known_types_embed.cc

Restore include style fix (e3da722b) that has been trampled by
auto-generation of well_known_types_embed.cc

* Fixed cross compilations with the Autotools build

Pull request #2517 caused cross compilations to start failing, because
the js_embed binary was being built to run on the target platform
instead of on the build machine. This change updates the Autotools build
to use the AX_PROG_CXX_FOR_BUILD macro to find a suitable compiler for
the build machine and always use that when building js_embed.

* Minor fix for autocreated object repeated fields and maps.

- If setting/clearing a repeated field/map that was objects, check the class
  before checking the autocreator.
- Just to be paranoid, don’t mutate within copy/mutableCopy for the autocreated
  classes to ensure there is less chance of issues if someone does something
  really crazy threading wise.
- Some more tests for the internal AutocreatedArray/AutocreatedDictionary
  classes to ensure things are working as expected.
- Add Xcode 8.2 to the full_mac_build.sh supported list.

* Fix generation of extending nested messages in JavaScript (#2439)

* Fix generation of extending nested messages in JavaScript

* Added missing test8.proto to build

* Fix generated code when there is no namespace but there is enum definition.

* Decoding unknown field should succeed.

* Add embed.cc in src/Makefile.am to fix dist check.

* Fixed "make distcheck" for the Autotools build

To make the test pass I needed to fix out-of-tree builds and update
EXTRA_DIST and CLEANFILES.

* Remove redundent embed.cc from src/Makefile.am

* Update version number to 3.2.0-rc.1 (#2578)

* Change protoc-artifacts version to 3.2.0-rc.1

* Update version number to 3.2.0rc2

* Update change logs for 3.2.0 release.

* Update php README

* Update upb, fixes some bugs (including a hash table problem). (#2611)

* Update upb, fixes some bugs (including a hash table problem).

* Ruby: added a test for the previous hash table corruption.

Verified that this triggers the bug in the currently released
version.

* Ruby: bugfix for SEGV.

* Ruby: removed old code for dup'ing defs.

* Reverting deployment target to 7.0 (#2618)

The Protobuf library doesn’t require the 7.1 deployment target so
reverting it back to 7.0

* Fix typo that breaks builds on big-endian (#2632)

* Bump version number to 3.2.0