Ant build: Use separate property for DLL helper files.

(Such as OlympusIX3Control.)

git-svn-id: https://valelab.ucsf.edu/svn/micromanager2/trunk@13788 d0ab736e-dc22-4aeb-8dc9-08def0aa14fd
git-svn-id: https://valelab.ucsf.edu/svn/micromanager2/trunk@13789 d0ab736e-dc22-4aeb-8dc9-08def0aa14fd
git-svn-id: https://valelab.ucsf.edu/svn/micromanager2/trunk@13790 d0ab736e-dc22-4aeb-8dc9-08def0aa14fd