* 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

* Down-integrate internal changes

* Update generated code for php, objc and csharp.

* Add missing dependency in conformance_php

* 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

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.

The failure lists were falling out of date because the
tests would pass even if people forgot to remove failures
from the list.

This involved fixing a few important bugs in the
Ruby implementation -- mostly cases of mixing
upb field types and descriptor types (upb field
types do not distinguish between int/sint/fixed/sfixed
like descriptor types do).

Also added protobuf-specific exceptions so parse
errors can be caught specifically.

Change-Id: Ib49d3db976900b2c6f3455c8b88af52cfb86e036

This allows us to enable conformance tests even when we know
that some tests are failing and need to be fixed.

Change-Id: I372f43663008747db6f2b2cf06e6ffa4c6d85b2d

Change-Id: I85675bfcd7697bb058b9af475445a6bfdd7fd967

Change-Id: I4c81808e6ace77d2b5737a43417045321b0b10f0

This is necessary for testing on iOS.

Change-Id: I54ec1e3aa2e9fbfff9a6cd6580920a6a62069b63