* 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.

We ran into problems with precompiled protoc binaries not working on
some systems because of the dependence on a dynamically linked
libatomic. However, I found that linking against libatomic is not
actually necessary in our protoc build environment. Inside configure.ac
there's a test which figures out if we need to pass -latomic, and it
does this by attempting to build a test binary. That binary was failing
to build, but it turns out this was because we need to pass -std=c++11,
not -latomic.

This fixes #5875.

* Allow bytes field to be longer than 16000 bytes

* Remove empty line

We need to mark messages as final soon, but before we do that we need to
provide a temporary opt-out mechanism to accommodate existing code that
inherits from generated messages. For 3.7.1 let's stop marking messages
final but in 3.8 we can reintroduce "final" with an opt-out option.

Down integrate to Github

The removed variable here is actually used breaking downstream bazel
builds.

Signed-off-by: Mickaël Schoentgen <contact@tiger-222.fr>

The bazel-bin/ and bazel-genfiles/ directories are going to be merged
soon. That change was causing some test failures on Windows, and I
believe it is because the logic for locating test data files was getting
confused and mistakenly looking for them under bazel-bin/. This commit
updates that logic to look for a more specific file (descriptor.cc)
which does not appear under any Bazel-related directories.

It sounds like the more official solution is to use the Bazel runfiles
library (i.e. //tools/cpp/runfiles). However, I decided not to do that
because we currently still support multiple build systems, and if we
used a separate solution for Bazel then I suspect we would need even
more #ifdefs in the code to handle the different systems.

This should fix #5717 and ensure that this header gets installed
properly on Windows.

Undelete python/google/protobuf/pyext/proto2_api_test.proto that was accidentally removed from file_list

* add check for reserved keywords in extensions

* add all reserved keywords

* use string without std::

* add test and update name in lite version

* test updates

* Replace strptime with custom implementation

* Fix ruby strptime

* Fix test

* Fix ruby conformance test

* Use mktime

* Remove EmptyFieldMask from failed conformance test list

also add useful Span-based methods for ByteString

Revert "Updating Iterators to be compatible with C++17 in MSVC"

Update CONTRIBUTING.md to recommend applying the appropriate labels

* Fix macros in header of generated code

* Define PROTOBUF_MIN_PROTOC_VERSION in port_def.inc
* Remove duplicated GOOGLE_PROTOBUF_MIN_LIBRARY_VERSION from common.h

* Send error if the error has been defined

* Undef the new macro

Make the C# benchmarks non-packable

Ruby error messages in 3.7.x