Add the `revng::cantFail` function which allows to wrap functions with
`std::error_code` and check their result. This is analogous to
`llvm::cantFail` for `llvm::Error`.
Move the local path normalization process to a stand-alone function. Fix
a bug that caused relative paths to not be properly resolved due to
missing `true` in `remove_dots`.
Giacomo Vercesi