test=develop, update protobuf in Dockerfile used by CI

tools/manylinux1/Dockerfile.x64

@@ -31,10 +31,10 @@ RUN wget --no-check-certificate -qO- https://storage.googleapis.com/golang/go1.8
 ENV GOROOT=/usr/local/go GOPATH=/root/gopath
 ENV PATH=${GOROOT}/bin:${GOPATH}/bin:${PATH}
 
-# protobuf 3.1.0
-RUN cd /opt && wget -q --no-check-certificate https://github.com/google/protobuf/releases/download/v3.1.0/protobuf-cpp-3.1.0.tar.gz && \
-    tar xzf protobuf-cpp-3.1.0.tar.gz && \
-    cd protobuf-3.1.0 && ./configure && make -j4 && make install && cd .. && rm -f protobuf-cpp-3.1.0.tar.gz
+# protobuf 3.6.1
+RUN cd /opt && wget -q --no-check-certificate https://github.com/google/protobuf/releases/download/v3.6.1/protobuf-cpp-3.6.1.tar.gz && \
+    tar xzf protobuf-cpp-3.6.1.tar.gz && \
+    cd protobuf-3.6.1 && ./configure && make -j4 && make install && cd .. && rm -f protobuf-cpp-3.6.1.tar.gz
 
 RUN wget https://raw.githubusercontent.com/PaddlePaddle/Paddle/develop/python/requirements.txt -O /root/requirements.txt