Build system: add single-threaded compile mode to test script

scripts/test.sh

@@ -15,6 +15,13 @@
 # version 3 along with this program.
 # If not, see https://www.gnu.org/licenses/agpl-3.0.en.html
 
+if [ "$(tr '[:upper:]' '[:lower:]' <<< $SINGLE)" = "yes" ]; then
+    echo "Building tests in single-threaded mode."
+    WAIT_ANYWAY="wait"
+else
+    WAIT_ANYWAY=""
+fi
+
 if [ -z "$CXX" ]; then
     CXX="c++"
 fi
@@ -44,6 +51,7 @@ COMPILE_COMMANDS=(
 for command in ${!COMPILE_COMMANDS[@]}; do
     echo "${COMPILE_COMMANDS[command]}"
     ${COMPILE_COMMANDS[command]} &
+    $WAIT_ANYWAY
 done
 
 wait