[ORC] Move CWrapperFunctionResult out of the detail:: namespace.

This type has been moved up into the llvm::orc::shared namespace.

This type was originally put in the detail:: namespace on the assumption that
few (if any) LLVM source files would need to use it. In practice it has been
needed in many places, and will continue to be needed until/unless
OrcTargetProcess is fully merged into the ORC runtime.