BUG: Do not convert to make-escaped path for internal APIs

The KWSys SystemTools::ConvertToOutputPath method can add makefile
escape characters not suitable for passing paths to internal APIs.
Drop calls to it from ITK.

Change-Id: I124d6cea6e004ad47deed17379ca50392c0105b7
Merge topic 'no-ConvertToOutputPath'

fcd7463 BUG: Do not convert to make-escaped path for internal APIs