config.h is becoming internal

Hi LLVM developers and embedders,

This is a heads up to let you know that the llvm/Config/config.h header is becoming internal to the LLVM core source tree. As such, the header will no longer be installed, and is not to be used by anything under include/.

The cleanly namespaced llvm/Config/llvm-config.h continues to remain available to external and side-by-side projects like clang, and is the upgrade path if you were previously depending on config.h.

This is part of the 3.5 goal for library-friendly headers, resolving a class of issues where definitions from LLVM's config.h conflicted with other projects.

Please update your out-of-tree* LLVM-based projects appropriately in short order as the final uses have been fixed throughout upstream LLVM projects and it's time to switch. Thanks for bearing with the changes!

* You can still include config.h from external modules/passes which are imported and built strictly from within the LLVM source tree.