Fix line buffering in test output

tools/ctest_retry.bash

@@ -43,6 +43,8 @@ done
 
 total=$RETRIES
 cd $TESTDIR
+export RCUTILS_CONSOLE_STDOUT_LINE_BUFFERED=1
+
 echo "Retrying Ctest up to " $total " times."
 for ((i=1;i<=total;i++))
   do