* Install rake compiler

* Add kokoro config to build ruby gem on linux

* Rename from linix to linux

* Fix prepare_build.sh name

* Clean up

* Install bundler

* Install bundler

* Use c99 in order to build gem on mingw-32 on ruby 2.0.0

See https://github.com/rake-compiler/rake-compiler-dock/issues/4

* Move c99 config to extcofig.rb

* Add files to build ruby artifact for mac on kokoro

* Move ruby specific stuff to ruby dir

This configuration builds both 32-bit and 64-bit binaries for Mac OS X.
One thing I had to change was to increase our minimum supported version
for 10.7 to 10.9, because 10.9 (Mavericks) appears to be the earliest
version supporting C++11.

* Work around MSVC issue with std::atomic initialization

MSVC seems to have a bug where it does not use constant initialization
for std::atomic, which ends up causing crashes during initialization.
This change introduces a workaround by putting the std::atomic inside a
union, which causes the compiler to use constant initialization for it.

* Added an AppVeyor test for static linking with MSVC

This should make it easy to automatically build 32-bit and 64-bit
Windows protoc binaries.

* Use legacy name in php runtime

Old generated code cannot work with new runtime, because the new runtime
assumes new class name for nested message. For details see #4738.

* Remove unused method

Updated the change log with changes for 3.6.0

Cherry-picked XCode 10 fixes into 3.6.x branch

* Update code to work for Xcode 10b

* Update README and test scripts to mention that Xcode 7 is no longer supported

Require C++11 and pass -std=c++11

This commit updates the Autotools build to require a C++11 compiler and
explicitly pass -std=c++11. This seems to be necessary for enabling
C++11 support in older compilers.

Cherry-pick changes into 3.6.x

These methods are used by grpc

Removed duplicate using statement from ReflectionUtil.cs

Fix php memory leak test (#4692)

Fixed JS parsing of unspecified map keys

We need to use a default of 0 when parsing unspecified map keys, instead
of failing an assertion.

This change was written by Michael Aaron (michaelaaron@google.com) but I
am cherry-picking it directly instead of waiting for the next sync of
Google-internal changes.

Cherry-pick php generated code changes into 3.6.x

In old generated code, the constructor of message doesn't provide a
default null to parent's constructor. Previously, in c extesnion, this
case was not handled.

* uses namespaces for nested messages and enums

* fixes namespaces for PHP dist

* fixes namespace for Descriptors, adds Cardinality and Kind

* fixes nested namespaces for reserved words and adds tests

* adds tests and generator fix for php class prefixes

* fixes escaping of protobuf packages, enum comments, misc others

* nice refactor of generated code

* adds class files for backwards compatibility

* simplifies code with templates

* adds compatibility files to makefile

* cleanup of generator and fixes nested namespace bug

* regenerates proto types

* remove internal BC classes

* adds deprecated warning, adds methods back

* simplifies if statement

* fixes dist files

* addresses review comments

* adds back TYPE_URL_PREFIX constant

* adds @deprecated to old nested class files

* skips tests which require a separate process when protobuf.so is enabled

* Adds tests for legacy nested classes that do not require separate processes to test

* uses legacy names for GPBUtil message check

* adds block for IDE @deprecated message

* Namespace for nested message/enum in c extension

* Remove unused code

* PHP array constructors for protobuf messages

* removes Descriptor from error message

* allows mergeFrom to accept an array

* only use initWithDescriptor if instanceof MapEntry

* adds doc comments

* removes ability for constructors to take arrays for submessages

* Revert "allows mergeFrom to accept an array"

This reverts commit b7b72182d561634af12c5c5c56a7cda3b33241f9.

* makes mergeFromArray protected and fixes mergeFrom whitespace

* Separates merging from JSON and merging from PHP array

* removes well-known types and json keys from array construction

* Addresses PR review comments

* cleans up tests

* fixes exception messages

* Adopt ruby_package in ruby generated code.

* Add test for ruby_package

* Adopt php_metadata_namespace in php code generator

The php_metadata_namespace is corresponded to the relative directory of
the metadata file. e.g., previously, the metadata file of foo.proto was
GPBMetadata/Foo.php. If the php_metadata_namespace is "Metadata\\Bar",
the metadata file will be Metadata/Bar/Foo.php.

* Handle empty php_metadata_namespace

Make sure to delete temporary maps used by FileDescriptorTables

I ran the tcmalloc heap checker in draconian mode, and it reported some
heap allocations that were still reachable when protobuf-test exited. To
fix that, I updated FileDescriptorTables to make sure its temporary
heap-allocated maps are deleted when it is destroyed.

Update version number to 3.6.0