* Fix empty FieldMask json encoding/decoding

* Add failed test to python's conformance failure list

* Fix Any json encoding/decoding for ruby.

* Revert unnecessary changes

* Fix field mask for php in json

* Update byte size

ObjC doesn't support them, but this ensure when tests are added
they will be handled correctly.

The conformance.proto was updated in PR #5566

* Down-integrate internal changes to github.

* Fix BUILD file and regenerate csharp descritpor

* Down-integrate internal changes to github.

* fix csharp conformance test

* add comments in conformance.proto for text format

* fix comments

* fix comments, re-generated csharp file

* fix comments, re-generated csharp file

Even though the comments were indented to appear to go with the jspb
case/field, protoc doesn't collect comments like that, so these "hanging"
comments actually "attach" to the next thing added to each.  Looking at
https://github.com/protocolbuffers/protobuf/pull/5566 you see where
the generated code picked up the comment on the wrong field.

* Down-integrate internal changes to github.

* fix python conformance test

* fix csharp conformance test

* add back java map_lite_test.proto's optimize for option

* fix php conformance test

Revert "Revert "Enable the ignore_unknown_field option in the Ruby unmarshal options" (#5511)" (#5533)

* Revert "Revert "Enable the ignore_unknown_field option in the Ruby unmarshal options" (#5511)"

This reverts commit be1716a6.

* Separate ruby conformance test on Mac

* Fix shell syntax

* Fix test

* Fix Any json encoding/decoding in php

* Fix comments

This adds the ability for the MRI Ruby library to optionally pass in a
ignore_unknown_fields option when decoding JSON. The functionality was
added upstream in upb, this change exposes that option.

* Down-integrate internal changes

* Update generated code for php, objc and csharp.

* Add missing dependency in conformance_php

* Adopt upb change for timestamp and duration json to php

* Remove unused code

* Re-sync upb

* Fix php implementation timestamp json parsing

* Fix strptime use local timezone on mac.

* Remove succeeding tests

* Resync

* Add tests for values

* Fix php tests

* Fix encoder handlers change default value

Previously, oneofsubmsg_handler and submsg_handler change zval's default value directly.
The fix use REPLACE_ZVAL_VALUE which create a copy of parsed value and assign it to zval.

* Fix conformance running nothing issue

This change adds a source dependency of the test suite implementaion
class in the main function. For generality reason, the main function is
moved to the file of the test suite implemetation.  New test suite
implementation will need to implement the main function.
In order to make it easy for test suite implementation to implement the
main function, this change also refactor out the common code out of the
main function.

* Fix typo

* Add missing reference to conformanc_test_impl.cc in Makefile

* Update conformance failure list

1. Fix C++ tests.
  * Add missing files to Makefile.am and fix distcheck in tests.sh
  * Remove BUILT_SOURCES from conformance/Makefile.am.
  * Add some missing override keyword.
  * Add a type cast to int64 because our StrCat() in stubs can't handle size_t.
2. Fix Java tests.
  * Add missing test dependency on guava in pom.xml.
  * Include newly referenced test data in test resources.
  * Manually fix map_lite_test.proto which is overwritten because it's mapped
    from map_test.proto in google3.
  * Add back "optimize_for = LITE_RUNTIME" which is still needed to keep the
    opensource test passing as it's still running lite tests.
  * Add a type cast in newBuilder() because without it the code doesn't compile
    with openjdk javac 1.8 (the compiler can't figure if it's the right type
    due to complex generic typing).
3. Fix Python tests.
  * Remove/replace references to <hash_map>.
  * Suppress more warnings in setup.py.
  * Replace incorrect header inclusion for google/protobuf/proto_api.h.
  * Add strings::EndsWith to google/protobuf/stubs/strutil.h because it's
    referenced in the updated python C extension code.
  * Replace proto2 with google::protobuf. The proto2 name is leaked to
    opensource because we removed the subsitition rule for proto2 namespace
    but only fixed C++ source code and forgot to update python C extension code.

* Give a unique category to each test.

This change introduce a TestCategory enum to ConformanceRequest. Existing tests
are divided into three categories: binary format test, json format test and json
format (ignore unknown when parsing) test. For the previous two categories, there
is no change to existing testee programs. For tests with the last category, testee programs
should either enable ignoring unknown field during json parsing or skip the test.

* Fix python test

* Fix java

* Fix csharp

* Update document

* Update csharp generated code

* Add conformance test for php c back

php c extension has different result for conformance test for different
php version and architecture. Try to add conformance back for php 7.1 c extension first.

* Disable conformance test for c extension on 32-bit architecture
32-bit and 64-bit have different failing tests

* Fix typo

* Remove/replace travis references.

* Enable ignoring unknown in json parsing in php

* Update generated descriptor files

* Update failure list for other languages.

* Remove unnecessary php files

This commit adds two entries to the conformance failure list for Ruby.
It seems that these particular test cases have been failing since they
were introduced in 5140bae3, so there
has not been any regression.

We no longer need this, now that we have finished the switch to C++11
and are using std::unique_ptr.

These statements pulled a bunch of symbols from the std namespace into
the global namespace. This commit removes all of them except for
std::string, which is a bit trickier to remove.

Add preserve UnknownFields
Compare floating point values bitwise
Add auto-generated header to C# generated files