Remove ant.properties

The properties currently therein are duplicates of those in
project.properties.

The build.xml file first loads properties from ant.properties, then from
project.properties, so ant.properties is redundant.

The file's existance was a maintenance issue.  The past couple times
when the property "target" was updated in project.properties, the
property was overlooked in ant.properties, so ant builds would fail when
Eclipse builds would succeed.