add gdb to docker image

docker/Dockerfile

@@ -38,14 +38,19 @@ RUN apt update && \
     cd stlink-1.5.1 && make clean && make release && \
     cd build/Release && make install && ldconfig
 
+# gdb
+
+RUN apt update && \
+    apt install -y --no-install-recommends \
+    python-dev && \
+    apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* && \
+    wget http://mirrors.kernel.org/ubuntu/pool/main/r/readline6/libreadline6_6.3-8ubuntu2_amd64.deb && \
+    dpkg -i libreadline6_6.3-8ubuntu2_amd64.deb && \
+    wget http://mirrors.kernel.org/ubuntu/pool/universe/g/gdb-arm-none-eabi/gdb-arm-none-eabi_7.10-1ubuntu3+9_amd64.deb && \
+    dpkg -i gdb-arm-none-eabi_7.10-1ubuntu3+9_amd64.deb
+
 COPY entrypoint.sh syntax_check.sh /
 
 RUN chmod +x /syntax_check.sh
 
 ENTRYPOINT ["/entrypoint.sh"]
-
-# apt install python-dev
-# wget http://mirrors.kernel.org/ubuntu/pool/main/r/readline6/libreadline6_6.3-8ubuntu2_amd64.deb
-# dpkg -i libreadline6_6.3-8ubuntu2_amd64.deb
-# wget http://mirrors.kernel.org/ubuntu/pool/universe/g/gdb-arm-none-eabi/gdb-arm-none-eabi_7.10-1ubuntu3+9_amd64.deb
-# dpkg -i gdb-arm-none-eabi_7.10-1ubuntu3+9_amd64.deb