docker: skip unavailable optional packages during build

Author: viyatb

optional_tools.sh

@@ -14,7 +14,13 @@ PACKAGES="theharvester \
           o-saft"
 
 if [ "$1" = "--download-only" ]; then
-  apt-get install -d -y $PACKAGES
+  install_args="-d -y"
 else
-  apt-get install -y $PACKAGES
+  install_args="-y"
 fi
+
+for package in $PACKAGES; do
+  if ! apt-get install $install_args "$package"; then
+    echo "[!] Skipping unavailable optional package: $package"
+  fi
+done