fix centos6.6 docker build with overlay

tools/dockerfile/grpc_artifact_protoc/Dockerfile

@@ -45,26 +45,21 @@ RUN yum install -y git \
                    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
+
+# Make yum install twice to overcome docker issue when using overlay storage driver.
+
+# We'll get and "Rpmdb checksum is invalid: dCDPT(pkg checksums)" error caused by
+# docker issue when using overlay storage driver, but all the stuff we need
+# will be installed, so for now we just ignore the error.
+# https://github.com/docker/docker/issues/10180
 RUN yum install -y devtoolset-1.1 \
                    devtoolset-1.1-libstdc++-devel \
-                   devtoolset-1.1-libstdc++-devel.i686
+                   devtoolset-1.1-libstdc++-devel.i686 || true
 
 # Start in devtoolset environment that uses GCC 4.7
 CMD ["scl", "enable", "devtoolset-1.1", "bash"]

tools/run_tests/artifact_targets.py

@@ -250,7 +250,7 @@ class ProtocArtifact:
       cxxflags = '-DNDEBUG %s' % _ARCH_FLAG_MAP[self.arch]
       ldflags = '%s' % _ARCH_FLAG_MAP[self.arch]
       if self.platform != 'macos':
-        ldflags += ' -static-libgcc -static-libstdc++ -s'
+        ldflags += '  -static-libgcc -static-libstdc++ -s'
       environ={'CONFIG': 'opt',
                'CXXFLAGS': cxxflags,
                'LDFLAGS': ldflags,