Move grpc installation from docker file to script.

test/distrib/cpp/run_distrib_test.sh

@@ -30,7 +30,13 @@
 
 set -ex
 
-cd $EXTERNAL_GIT_ROOT
+git clone https://github.com/grpc/grpc.git
+cd grpc && git submodule update --init
+
+cd third_party/protobuf && ./autogen.sh && \
+./configure && make -j12 && make check && make install && ldconfig
+
+cd ../.. && make -j12 && make install
 
 cd examples/cpp/helloworld
 

tools/dockerfile/distribtest/cpp_jessie_x64/Dockerfile

@@ -42,12 +42,4 @@ RUN apt-get update && apt-get install -y \
       pkg-config \
       unzip && apt-get clean
 
-RUN git clone https://github.com/grpc/grpc.git
-RUN cd grpc && git submodule update --init
-
-RUN cd grpc/third_party/protobuf && ./autogen.sh && \
-    ./configure && make -j12 && make check && make install && ldconfig
-
-RUN cd grpc && make -j12 && make install
-
 CMD ["bash"]