Dockerfile: speed up criu build
... in case we have more than one CPU, that is.
@@ -63,7 +63,7 @@ RUN mkdir -p /usr/src/criu \
&& curl -fsSL https://github.com/checkpoint-restore/criu/archive/${CRIU_VERSION}.tar.gz | tar -C /usr/src/criu/ -xz --strip-components=1 \
&& cd /usr/src/criu \
&& echo 1 > .gitid \
- && make install-criu \
+ && make -j $(nproc) install-criu \
&& cd - \
&& rm -rf /usr/src/criu
