I think you're on the right path looking at the lines specified in the error message.
I've uploaded copies of the files specified at the following links.
Check the line numbers in the error message and those surrounding it for any deviations. Post back with your findings.
C:\Users\Developer\sunspotfrcsdk\ant\configure.xml check around line 41
https://gist.github.com/jcorcoran/9633480
C:\Users\Developer\sunspotfrcsdk\build.xml check around line 42
https://gist.github.com/jcorcoran/9633445