* remove pass by reference for php setters

* comments out memory leak test

Both native_slot_merge and native_slot_merge_by_array have no return
type declared. GCC implicitly uses int as return type in such cases,
however, these functions are actually void.

In the generated code of previous versions, each php field is given an
initial value. In c extension, it was assumed that the field order in
the generated code is consistent with upb fields order, so that the
correct initial value can be bound to the correct upb field. However,
this may not be true. The order of fields in generated code is decided
by proto compiler, while the order of upb fields is decided by the hash
function used in c extension.
This PR fixes the issue by reset the initial value at runtime.

Use consistent hash across NDEBUG/!NDEBUG builds.

Rather than crashing on use (doh!) better to just declare this platform
is missing a proper hash_map/hash_set implementation and use
the std::map/std::set emulation.

Fixes regression introduced by #1913

* Remove using std::{set,map}

Fixes #3322.

[Ruby] fix floating point accuracy problem in Timestamp#to_f

* add Grpc Protobuf validation

Expose the initializer for unknown fields.

Note that the compatibility tests have had to cahnge as well, to
cope with internal changes. (The test project has access to
internals in the main project.)

Fixes #3209.

- Add a TryUnpack method which doesn't throw if the type is wrong
- Make GetTypeName public for easier determination of the message type

Fixes #3294.

* Add json encode/decode for php.

* Fix php conformance test on 32-bit machines.

* Fix conformance test for c extension.

* Fix comments

Add initialized as a reserved keyword as that's the actual property name

* Add scripts to build python wheel for linux.
Followed PEP513.

* Fix dist check for new added files.

* Update README for usage example.

* adds PHPDoc @return and @param for getters and setters respectively

* addresses changes in PR review

* adds documentation tests

* Update php_generator:

- Prepend \ to names where required
- Remove <pre> tags
- Update protobuf field comments

* Updates class files with the protobuf changes

* Addresses review comments

* removes Protobuf Type line from PHP generated classes

* fixes phpdoc test

* adds array types to phpdoc

Workaround the docker bug when compiling artifacts

Enusre public header and generated code have no implicit converion.

C++: Do not forward-declare dependencies in generated .h files

Updated links to use https

Howdy!

I just updated some links to use https instead of http.

Thanks! ^ _ ^

If we fail to get a descriptor just super the method resolving.

This should never happen, but if someone is swizzling or do other
hooking of methods, anything is possible, so this seems slighty
safer than they returning NO.

Update version number to 3.3.2

Cherry-pick bug fixes for php

That implementation of json is not being used - this extension is using
a json encoder/decoder provided by 'upb'.