Removed forward declaration of MemBlock class

Removed forward declaration of MemBlock class.

Declaration is in conflict with declaration `::strings::MemBlock`

Merge 3.6.x branch into master

* Remove protoc conditional properties

* Fix duplicate brace

the testMessageSetNullFail function was declared twice.
So I renamed one to testMessageSetNullFailMap

Remove the executable bit from several source code files

Fixed protobuf_generate output definition

Added `-y` flag to `sudo apt-get` command.

Add "override" keyword for overridden virtual functions

Add guards against bswap_XX redefnitions

* 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

This change helps both humans and linters to understand the unusual method of instantiating this global variable.

This potentially avoids compiler warnings.

update ScalaPB url

Use versions module from Skylib for version checking 

* Add files to build ruby artifact for mac on kokoro

* Move ruby specific stuff to ruby dir

Fix parameters declaration

protostream_objectwriter: fix bug when Any is directly embedded in a …

protostream_objectsource: preserve print options across Any.

* Added props to C# tools

* Add targets file to makefile.am

json: include field name in InvalidName status messages.

Signed-off-by: Harvey Tuch <htuch@google.com>

This came up when trying to round-trip the JSON<->proto3 conversion for
Envoy's envoy.admin.v2alpha.ConfigDump
(https://github.com/envoyproxy/envoy/blob/b903c1dc984593f8e95e0569c1503dc5d85fbe34/api/envoy/admin/v2alpha/config_dump.proto#L29).

Validated fix on the Envoy code base and via the provided unit test.
Signed-off-by: Harvey Tuch <htuch@google.com>

Fixes #4771. Based on the solution included in the issues from
@wangjinhua.

Validated this works with Envoy's /config_dump JSON rendering.
Signed-off-by: Harvey Tuch <htuch@google.com>

Signed-off-by: Harvey Tuch <htuch@google.com>

This is invaluable for chasing down the culprit in failed JSON -> proto
conversions. We often see in Envoy that a failed JSON (or indirectly via
YAML) configuration won't load but it's unclear why.
Signed-off-by: Harvey Tuch <htuch@google.com>

Disable thread local storage for OSX < 10.7

check provided size to check whether to export

Fix typo in the doc

Update issue templates

Add "override" for overridden virtual functions.
Please refer following issue for discussion on this.
https://github.com/google/protobuf/issues/67