Revert https://codereview.chromium.org/1291903002 (protobuf roll).

third_party/protobuf/protoc-artifacts/README.md

-# Build scripts that publish pre-compiled protoc artifacts
-``protoc`` is the compiler for ``.proto`` files. It generates language bindings
-for the messages and/or RPC services from ``.proto`` files.
-
-Because ``protoc`` is a native executable, the scripts under this directory
-build and publish a ``protoc`` executable (a.k.a. artifact) to Maven
-repositories. The artifact can be used by build automation tools so that users
-would not need to compile and install ``protoc`` for their systems.
-
-## Versioning
-The version of the ``protoc`` artifact must be the same as the version of the
-Protobuf project.
-
-## Artifact name
-The name of a published ``protoc`` artifact is in the following format:
-``protoc-<version>-<os>-<arch>.exe``, e.g., ``protoc-3.0.0-alpha-3-windows-x86_64.exe``.
-
-## System requirement
-Install [Apache Maven](http://maven.apache.org/) if you don't have it.
-
-The scripts only work under Unix-like environments, e.g., Linux, MacOSX, and
-Cygwin or MinGW for Windows. Please see ``README.md`` of the Protobuf project
-for how to set up the build environment.
-
-## To install artifacts locally
-The following command will install the ``protoc`` artifact to your local Maven repository.
-```
-$ mvn install
-```
-
-## Cross-compilation
-The Maven script will try to detect the OS and the architecture from Java
-system properties. It's possible to build a protoc binary for an architecture
-that is different from what Java has detected, as long as you have the proper
-compilers installed.
-
-You can override the Maven properties ``os.detected.name`` and
-``os.detected.arch`` to force the script to generate binaries for a specific OS
-and/or architecture. Valid values are defined as the return values of
-``normalizeOs()`` and ``normalizeArch()`` of ``Detector`` from
-[os-maven-plugin](https://github.com/trustin/os-maven-plugin/blob/master/src/main/java/kr/motd/maven/os/Detector.java).
-Frequently used values are:
-- ``os.detected.name``: ``linux``, ``osx``, ``windows``.
-- ``os.detected.arch``: ``x86_32``, ``x86_64``
-
-For example, MingGW32 only ships with 32-bit compilers, but you can still build
-32-bit protoc under 64-bit Windows, with the following command:
-```
-$ mvn install -Dos.detected.arch=x86_32
-```
-
-## To push artifacts to Maven Central
-Before you can upload artifacts to Maven Central repository, make sure you have
-read [this page](http://central.sonatype.org/pages/apache-maven.html) on how to
-configure GPG and Sonatype account.
-
-You need to perform the deployment for every platform that you want to
-suppport. DO NOT close the staging repository until you have done the
-deployment for all platforms. Currently the following platforms are supported:
-- Linux (x86_32 and x86_64)
-- Windows (x86_32 and x86_64) with
- - Cygwin with MinGW compilers (both x86_32 and x86_64)
- - MSYS with MinGW32 (x86_32 only)
-- MacOSX (x86_32 and x86_64)
-
-Use the following command to deploy artifacts for the host platform to a
-staging repository.
-```
-$ mvn clean deploy -P release
-```
-It creates a new staging repository. Go to
-https://oss.sonatype.org/#stagingRepositories and find the repository, usually
-in the name like ``comgoogle-123``.
-
-You will want to run this command on a different platform. Remember, in
-subsequent deployments you will need to provide the repository name that you
-have found in the first deployment so that all artifacts go to the same
-repository:
-```
-$ mvn clean deploy -P release -Dstaging.repository=comgoogle-123
-```
-
-A 32-bit artifact can be deployed from a 64-bit host with
-``-Dos.detected.arch=x86_32``
-
-When you have done deployment for all platforms, go to
-https://oss.sonatype.org/#stagingRepositories, verify that the staging
-repository has all the binaries, close and release this repository.
-
-### Tips for deploying on Linux
-We build on Centos 6.6 to provide a good compatibility for not very new
-systems. We have provided a ``Dockerfile`` under this directory to build the
-environment. It has been tested with Docker 1.6.1.
-
-To build a image:
-```
-$ docker build -t protoc-artifacts .
-```
-
-To run the image:
-```
-$ docker run -it --rm=true protoc-artifacts
-```
-
-The Protobuf repository has been cloned into ``/protobuf``.
-
-### Tips for deploying on Windows
-Under Windows the following error may occur: ``gpg: cannot open tty `no tty':
-No such file or directory``. This can be fixed by configuring gpg through an
-active profile in ``.m2\settings.xml`` where also the Sonatype password is
-stored:
-```xml
-<settings>
-  <servers>
-    <server>
-      <id>ossrh</id>
-      <username>[username]</username>
-      <password>[password]</password>
-    </server>
-  </servers>
-  <profiles>
-    <profile>
-      <id>gpg</id>
-      <properties>
-        <gpg.executable>gpg</gpg.executable>
-        <gpg.passphrase>[password]</gpg.passphrase>
-      </properties>
-    </profile>
-  </profiles>
-  <activeProfiles>
-    <activeProfile>gpg</activeProfile>
-  </activeProfiles>
-</settings>
-```
-
-### Tested build environments
-We have succesfully built artifacts on the following environments:
-- Linux x86_32 and x86_64:
- - Centos 6.6 (within Docker 1.6.1)
- - Ubuntu 14.04.2 64-bit
-- Windows x86_32: MSYS with ``mingw32-gcc-g++ 4.8.1-4`` on Windows 7 64-bit
-- Windows x86_64: Cygwin64 with ``mingw64-x86_64-gcc-g++ 4.8.3-1`` on Windows 7 64-bit
-- Mac OS X x86_32 and x86_64: Mac OS X 10.9.5