* Rolled forward again with "Updated upb from defcleanup branch..."

Revert "Revert "Updated upb from defcleanup branch and modified Ruby to use it (#5539)" (#5848)"

This reverts commit 1568deab.

* A few more merge fixes.

* Updated for defcleanup2 branch.

* Fixed upb to define upb_decode().

* Fixed names of nested messages.

* Revert submodule.

* Set -std=gnu90 and fixed warnings/errors.

Some of our Kokoro tests seem to run with this level of warnings,
and the source strives to be gnu90 compatible.  Enforcing it for
every build removes the possibility of some errors showing up in
Kokoro/Travis tests only.

* Fixed remaining warnings with gnu90 mode.

I tried to match warning flags with what Ruby appears to do
in our Kokoro tests.

* Initialize values registered by rb_gc_register_address().

* Fixed subtle GC bug.

We need to initialize this marked value before creating the instance.

* Truly fix the GC bug.

* Updated upb for mktime() fix.

* Removed XOPEN_SOURCE as we are not using strptime().

* Removed fixed tests from the conformance failure list for Ruby.

* Fixed memory error related to oneof def names.

* Picked up new upb changes re: JSON printing.

* Uncomment concurrent decoding test.

Prior to this CL, creating an empty message object would create
two empty string objects for every declared field.  First we
created a unique string object for the field's default.  Then
we created yet another string object when we assigned the
default value into the message: we called #encode to ensure
that the string would have the correct encoding and be frozen.

I optimized these unnecessary objects away with two fixes:

1. Memoize the empty string so that we don't create a new empty
   string for every field's default.
2. If we are assigning a string to a message object, avoid creating
   a new string if the assigned string has the correct encoding and
   is already frozen.

* Add changelog for 3.9.x

* Revert "Make php message class final to avoid mocking (#6277)" (#6324)

This reverts commit 7f84a943.
This is just temporary. Eventually, we still want to roll forward this
change. Some users are complaining they need more time to clean up their
code.

* Update extract_includes.bat.in

File io_win32.h is not in directory google\protobuf\stubs under directory google\protobuf\io

* Set oneof case in array constructor (#6351)

Forgot to set it previously.

* Update protobuf version (#6366)

* Drop building wheel for python 3.4 (#6406)

https://github.com/matthew-brett/multibuild/pull/240

* Fix binary compatibility in FieldCodec factory methods (#6380) (#6424)

* Fix binary compatibility in FieldCodec factory messages

* Make default value parameter for current factories required

* Route old methods through default value overloads

* Remove ExtensionRegistry.Add(params) overload

* Rename ExtensionRegistry.Add(IEnumerable<Extension>) overload to AddRange

* Edit naming of parameters in Extension classes

* * Fix add API warnings to docs for extension APIs
* Rename internal ExtensionSet.GetValue to TryGetValue

* Disable javadoc error (#6371)

* Disable javadoc error

Actual fixes of the javadoc will be followed up

* Remove duplicated configuration

* Update javadoc plugin version

* Updated Bazel test script to use most recent Bazel version (#6413) (#6433)

I'm not exactly sure why, but this fixes the failing Bazel presubmit
test. Using the most recent version seems like a good idea anyway so
that we can make sure we're compatible with any new Bazel changes.

* [bazel] Add fixes for --incompatible_load_{cc,java,proto}_rules_from_bzl

* No need to update version in generated code (#6471)

generate_descriptor will handle that

* Update protobuf version (#6472)

* support hashes for struct initalizers

* convert hash keys to string

* update tests

* add extra asserts

This changes to_time to use Ruby's built in Time.at with nanos support
rather than calculating a float and passing it to Time.at. The new
version runs about 3 times faster than the original version and
allocates fewer objects.

Warming up --------------------------------------
    protobuf#to_time    57.296k i/100ms
      faster#to_time   133.229k i/100ms
Calculating -------------------------------------
    protobuf#to_time    635.361k (± 2.1%) i/s -      3.209M in   5.052169s
      faster#to_time      1.873M (± 3.3%) i/s -      9.459M in   5.055169s

Comparison:
      faster#to_time:  1873368.8 i/s
    protobuf#to_time:   635361.4 i/s - 2.95x  slower

Calculating -------------------------------------
    protobuf#to_time   326.000  memsize (   126.000  retained)
                         7.000  objects (     2.000  retained)
                         0.000  strings (     0.000  retained)
      faster#to_time    86.000  memsize (     0.000  retained)
                         1.000  objects (     0.000  retained)
                         0.000  strings (     0.000  retained)

Comparison:
      faster#to_time:         86 allocated
    protobuf#to_time:        326 allocated - 3.79x more

* Change int64 json encoding to be string for php and ruby

* Fix ruby test

* Sync upb change

value_field_typeclass should be a enum module, not EnumDescriptor
object.

Also expanding tests for enum valued maps.

Fixes #4580
Signed-off-by: Sorah Fukumori <her@sorah.jp>

This reverts commit 6d96493b.

In general, I think it will help us to debug issues if we have less C
code and more Ruby code.  This method can be implemented in pure Ruby,
so this commit converts it to pure Ruby.

* Custom mktime to fix issue on mac

* Remove succeeded tests from failure list

* add wrapper type helpers

* add check for _as_value suffix

* add implicit time conversion

* add duration

* add init test

* more tests

* add type check and alternative c type check

* add rational and bigdecimal

* use rb_obj_is_kind_of

* use native time check

* chain implicit conversions

* remove unused variable

* Update version number to 3.7.1

* Update version number in port_def.inc

OSX has deprecated OpenSSL, so we need to install it via Homebrew and
build against that version when we build Ruby.

* Allow bytes field to be longer than 16000 bytes

* Remove empty line

* Replace strptime with custom implementation

* Fix ruby strptime

* Fix test

* Fix ruby conformance test

* Use mktime

* Remove EmptyFieldMask from failed conformance test list

* Add conformance test for nested listvalue

* Fix upb for parsing repeated Value/ListValue

* Add failed repeated ListValue conformance test into php failure list

* Encode empty ListValue

* Update mac ruby conformance failure list

* add check for overflow

* de-nestify

* break long lines

* Fix ruby continuous tests

* Fix compatibility test

This reverts commit 37581380.