add gcc-c++ to avoid missing g++ during bcrypt build

docker/Dockerfile

@@ -38,6 +38,7 @@ RUN \
                     java-$ES_JAVA_VERSION \
                     glibc-devel \
                     gcc \
+                    gcc-c++ \
                     libstdc++ \
                     supervisor \
                     libffi-devel \
@@ -165,4 +166,4 @@ VOLUME /opt/mozdef/envs/mozdef/data
 # 9200 = Elasticsearch
 EXPOSE 80 3002 5672 15672 8080 8081 9090 9200
 
-CMD supervisord -n -c /etc/supervisor/conf.d/supervisor.conf
+CMD supervisord -n -c /etc/supervisor/conf.d/supervisor.conf