PHP: fixed typo in message.c

Add support for libc++ on Windows.

`update_file_lists.sh` depends on Bash features, thus needs Bash sebang.

Blacklist all WELL_KNOWN_PROTOS from Bazel C++ code generation.

Adds an option in C++ JSON parser to ignore unrecognized enum values

Merge 3.5.x to master

This prevents the Bazel `CcProtoAspect` from generating and linking
C++ object code for these files. Without this blacklist, symbols for
protobuf types depended on by `libprotobuf` may be defined multiple
times and violate the ODR rule.

Fixes https://github.com/google/protobuf/issues/4311

This lets all values of `WELL_KNOWN_PROTOS` be treated the same with
regard to Bazel's protobuf blacklisting.

I noticed that running this script as `./update_file_lists.sh` on MacOS
was corrupting `cmake/extract_includes.bat.in`. Forcing the shell to
Bash fixes the generated file output.

 Added instruction for existing ZLIB configuration

Added instruction for existing ZLIB configuration

Using two configuration flags `DZLIB_INCLUDE_DIR` and `DZLIB_LIB` we can locate an existing ZLIB on the system

Rename a shadowed variable.

Shadowed variables can cause readability issues. Ensure a shadowed
variable isn't used in header files which may be used in a dependent
project that explicitly disables them.

Remove unused output_file variable from js_embed

unrecognized string values in enum fields as default ones.

* Cython's stack does not have .py file name. Only check filenames when end with .py for _CalledFromGeneratedFile()

Sync internal benchmark changes

Remove use of GOOGLE_FALLTHROUGH_INTENDED from protobuf.

Fixes #4277

Chrome is running into two issues with the use of this macro
in open-source protobuf (https://crbug.com/809157):

1. GOOGLE_FALLTHROUGH_INTENDED is defined to nothing on __APPLE__
   platforms, which blocks us from enabling -Wimplicit-fallthrough
   on Mac and iOS. (We use a hermetic self-built modern clang,
   so whatever Xcode bug that exclusion might be for doesn't apply
   to us.)

2. It's in a public header file, and it's included in a public header file.
   When clang suggests adding [[clang::fallthrough]], it checks if it knows of
   a macro expanding to that and if so, suggests inserting that. Since lots of
   chrome code includes protobuf headers, it often suggests inserting
   GOOGLE_FALLTHROUGH_INTENDED (from protobuf) instead of the correct
   FALLTHROUGH (from chrome's base).

Since the fallthrough doens't do anyting useful, just remove it.
Long ago, this might have had perf impact, but d64a2d99 added a
parsing fast path that calls this switch as slow fallback, so it should
be off the hot path nowadays.

No intended behavior change.

This is the public version of internal change 184824132.

Various CMake Update

Bazel: Support building with Java 9

Upgrade benchmark submodule

cf https://cmake.org/cmake/help/latest/policy/CMP0048.html#policy:CMP0048

We follow the findProtobuf.cmake naming convention
to ease the use of protobuf as cmake subproject

Fix link markup in third party list.

Create std::string in Arena memory

Fixes: #4256.

Bazel@HEAD supports Java 9.

The current code has one single issue with Java 9 compliance: the usage
of sun.misc package. We add jdk.unsupported module with --add-modules
compiler option for now. Long term, the usage of non public API should
be avoided.

To build with Java 9, build custom bazel version and issue:

  $ bazel --host_javabase=/usr/lib64/jvm/java-9-openjdk build \
    --javacopt='--release 9' \
    --java_toolchain=@bazel_tools//tools/jdk:toolchain_jdk9 \
   :protobuf_java

Haven't been able to make a repo case, but this should "fix" the problem
by avoid it completely.

- Move readOnlySemaphore_ into the .m file so it isn't exposed in any
  header.
- Move GPBGetObjectIvarWithField() also to go with the new limited
  visibility on the readOnlySemaphore_.