Update to most recent steam runtime.

utils/dockerbuilds/make_steam_image

@@ -2,17 +2,19 @@
 
 VALVEFILE=com.valvesoftware.SteamRuntime.Sdk-amd64,i386-scout-sysroot.Dockerfile
 VALVETAR=com.valvesoftware.SteamRuntime.Sdk-amd64,i386-scout-sysroot.tar.gz
+VALVE_SNAPSHOT=0.20200318.2
+
 DOCKERBASEIMAGE=steamrt_scout_amd64
 DOCKERLOCALIMAGE=wesnoth/wesnoth:steamrt-master
 DOCKERLOCALFILE=./travis/Dockerfile-base-steamrt
 
-if [ ! -f $VALVEFILE ]; then
-    wget http://repo.steampowered.com/steamrt-images-scout/snapshots/0.20190608.0/$VALVEFILE
+if [ ! -f "$VALVEFILE" ]; then
+    wget http://repo.steampowered.com/steamrt-images-scout/snapshots/"$VALVE_SNAPSHOT"/"$VALVEFILE"
 fi
-if [ ! -f $VALVETAR ]; then
-    wget http://repo.steampowered.com/steamrt-images-scout/snapshots/0.20190608.0/$VALVETAR
+if [ ! -f "$VALVETAR" ]; then
+    wget http://repo.steampowered.com/steamrt-images-scout/snapshots/"$VALVE_SNAPSHOT"/"$VALVETAR"
 fi
 
-docker build -t $DOCKERBASEIMAGE -f $VALVEFILE .
+docker build -t "$DOCKERBASEIMAGE" -f "$VALVEFILE" .
 
-docker build -t $DOCKERLOCALIMAGE -f $DOCKERLOCALFILE .
+docker build -t "$DOCKERLOCALIMAGE" -f "$DOCKERLOCALFILE" .

utils/dockerbuilds/travis/Dockerfile-base-steamrt

@@ -3,10 +3,11 @@ ENV DEBIAN_FRONTEND=noninteractive
 ARG BOOST_VERSION=1.66.0
 ARG BOOST_VERSION_=1_66_0
 
-RUN apt-get update && apt-get -y dist-upgrade && apt-get install -y scons libicu-dev libreadline-dev expect-dev
+RUN apt-get update
+RUN apt-get install -y scons libicu-dev libreadline-dev expect-dev
 
 RUN wget --max-redirect 3 https://dl.bintray.com/boostorg/release/${BOOST_VERSION}/source/boost_${BOOST_VERSION_}.tar.gz
 RUN mkdir -p /src/boost && tar zxf boost_${BOOST_VERSION_}.tar.gz -C /src/boost --strip-components=1
 RUN cd /src/boost && ./bootstrap.sh --with-libraries=iostreams,regex,system,filesystem,program_options,random,locale && ./b2 toolset=gcc-5 --layout=system link=static variant=release cxxflags='-fPIE -fstack-protector-strong' define=_FORTIFY_SOURCE=2 install
 
-RUN mkdir -p /staging/lib64 && cp /lib/libicu*.so.* /lib/x86_64-linux-gnu/libhistory.so.6 /staging/lib64/
+RUN mkdir -p /staging/lib64 && cp /usr/lib/libicu*.so.* /lib/x86_64-linux-gnu/libhistory.so.6 /staging/lib64/