Some files still contained the old University of Illinois Open Source
Licence header. This patch replaces that with the Apache 2 with LLVM
Exception licence.
Differential Revision: https://reviews.llvm.org/D107528
This patch extracts the RTTI part of llvm::ErrorInfo into its own class
(RTTIExtends) so that it can be used in other non-error hierarchies, and makes
it compatible with the existing LLVM RTTI function templates (isa, cast,
dyn_cast, dyn_cast_or_null) by adding the classof method.
Differential Revision: https://reviews.llvm.org/D39111