Tools: fix install-prereqs-ubuntu

make a function to return 1 if a dpkg find that a package is installed, O otherwise

Tools/environment_install/install-prereqs-ubuntu.sh

@@ -40,8 +40,12 @@ fi
 # update apt package list
 $APT_GET update
 
+function package_is_installed() {
+    return $(dpkg-query -W -f='${Status}' "$1" 2>/dev/null | grep -c "ok installed")
+}
+
 # Install lsb-release as it is needed to check Ubuntu version
-if ! dpkg-query -l "lsb-release"; then
+if package_is_installed "lsb-release" -ne 1; then
     echo "$sep"
     echo "Installing lsb-release"
     echo "$sep"
@@ -150,7 +154,7 @@ echo "Done!"
 echo "$sep"
 echo "Removing modemmanager package that could conflict with firmware uploading"
 echo "$sep"
-if dpkg-query -l "modemmanager"; then
+if package_is_installed "modemmanager" -ne 1; then
     $APT_GET remove modemmanager
 fi
 echo "Done!"