Fix build on Mono 2.0.
Fix build on Mono 2.0.

nant/nantcontrib,rmboggs/nantcontrib,rmboggs/nantcontrib,nant/nantcontrib,cgourlay/nantcontrib,cgourlay/nantcontrib,dahmage/nantcontrib,nant/nantcontrib,cgourlay/nantcontrib,dahmage/nantcontrib,rmboggs/nantcontrib,dahmage/nantcontrib