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

third_party/protobuf/protoc-artifacts/Dockerfile

-FROM centos:6.6
-
-RUN yum install -y git \
-                   tar \
-                   wget \
-                   make \
-                   autoconf \
-                   curl-devel \
-                   unzip \
-                   automake \
-                   libtool \
-                   glibc-static.i686 \
-                   glibc-devel \
-                   glibc-devel.i686
-
-# Install Java 8
-RUN wget -q --no-cookies --no-check-certificate \
-    --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" "http://download.oracle.com/otn-pub/java/jdk/8u45-b14/jdk-8u45-linux-x64.tar.gz" \
-    -O - | tar xz -C /var/local
-ENV JAVA_HOME /var/local/jdk1.8.0_45
-ENV PATH $JAVA_HOME/bin:$PATH
-
-# Install Maven
-RUN wget -q http://apache.cs.utah.edu/maven/maven-3/3.3.3/binaries/apache-maven-3.3.3-bin.tar.gz -O - | \
-    tar xz -C /var/local
-ENV PATH /var/local/apache-maven-3.3.3/bin:$PATH
-
-# Install GCC 4.7 to support -static-libstdc++
-RUN wget http://people.centos.org/tru/devtools-1.1/devtools-1.1.repo -P /etc/yum.repos.d
-RUN bash -c 'echo "enabled=1" >> /etc/yum.repos.d/devtools-1.1.repo'
-RUN bash -c "sed -e 's/\$basearch/i386/g' /etc/yum.repos.d/devtools-1.1.repo > /etc/yum.repos.d/devtools-i386-1.1.repo"
-RUN sed -e 's/testing-/testing-i386-/g' -i /etc/yum.repos.d/devtools-i386-1.1.repo
-RUN yum install -y devtoolset-1.1 \
-                   devtoolset-1.1-libstdc++-devel \
-                   devtoolset-1.1-libstdc++-devel.i686
-
-RUN git clone --depth 1 https://github.com/google/protobuf.git
-
-# Start in devtoolset environment that uses GCC 4.7
-CMD ["scl", "enable", "devtoolset-1.1", "bash"]