linux-clang-format, frozen: add p7zip-full

linux-clang-format/Dockerfile

@@ -1,4 +1,4 @@
 FROM ubuntu:18.04
 LABEL maintainer="citraemu"
 RUN apt-get update && apt-get -y full-upgrade
-RUN apt-get install -y git clang-format-6.0
+RUN apt-get install -y git clang-format-6.0 p7zip-full

linux-frozen/Dockerfile

@@ -2,7 +2,7 @@ FROM ubuntu:18.04
 LABEL maintainer="citraemu"
 RUN mkdir -p /tmp/pkgs
 COPY install_package.py /tmp/pkgs
-RUN apt-get update && apt-get install -y build-essential wget git python-launchpadlib ccache ninja-build
+RUN apt-get update && apt-get install -y p7zip-full build-essential wget git python-launchpadlib ccache ninja-build
 RUN cd /tmp/pkgs && python2 install_package.py \
     libsdl2-dev 2.0.7+dfsg1-3ubuntu1 bionic          \
     qtbase5-dev 5.9.3+dfsg-0ubuntu2 bionic           \