tdf#135211: fix crash Swarm Non Linear Solver with blank input

See bt here:
https://bugs.documentfoundation.org/attachment.cgi?id=163668

Change-Id: I78f59e420aa183399f650915c7c28a138b8ed444
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/99572
Tested-by: Julien Nabet <serval2412@yahoo.fr>
Reviewed-by: Julien Nabet <serval2412@yahoo.fr>
diff --git a/sccomp/source/solver/SwarmSolver.cxx b/sccomp/source/solver/SwarmSolver.cxx
index 0aa75b1..d59df28 100644
--- a/sccomp/source/solver/SwarmSolver.cxx
+++ b/sccomp/source/solver/SwarmSolver.cxx
@@ -508,6 +508,8 @@ void SAL_CALL SwarmSolver::solve()

    maStatus.clear();
    mbSuccess = false;
    if (!maVariables.getLength())
        return;

    maBounds.resize(maVariables.getLength());