swi-prolog: specify necessary host tools in setup-ubuntu.sh

scripts/setup-ubuntu.sh

@@ -42,6 +42,13 @@ PACKAGES+=" jq" # Needed by bintray upload script.
 PACKAGES+=" lua5.3" # Needed to build luarocks package.
 PACKAGES+=" python3-recommonmark" # needed for llvm-8 documentation
 PACKAGES+=" llvm-7-tools" # so we don't build llvm for build
+PACKAGES+=" openssl" # Needed by swi-prolog
+PACKAGES+=" libssl-dev:i386" # Needed by swi-prolog 32-bit
+PACKAGES+=" zlib1g-dev:i386"
+
+# Allow 32-bit packages.
+sudo dpkg --add-architecture i386
+sudo apt-get -yq update
 
 sudo DEBIAN_FRONTEND=noninteractive \
 	apt-get install -yq --no-install-recommends $PACKAGES