Include cmake and meson in the Dockerfile

The README contains an examples how afl can be used with cmake, but
cmake is not included in the Dockerfile. Thus, when running afl using
docker, one cannot invoke cmake from within the container.

This commit adds cmake and meson to the list of packages in the
Dockerfile that are installed when the docker image is generated.

Dockerfile

@@ -16,6 +16,8 @@ env NO_ARCH_OPT 1
 RUN apt-get update && \
     apt-get -y install --no-install-suggests --no-install-recommends \
     automake \
+    cmake \
+    meson \
     ninja-build \
     bison flex \
     build-essential \