CoreFoundation for PureDarwin

Based on Swift CoreFoundation from https://github.com/apple/swift-corelibs-foundation/tree/master/CoreFoundation.

Modified to work (more or less) when installed in a PureDarwin image.

(If you just want binary roots to add to a PureDarwin image, look here.)

Fixes

• Version set to 1348.28.0
• Removed CFURLSession and dependency on libcurl (and everything that depends on)
• Calls CFInitialize() at load time, so things actually work
• Adds an implementation of CFFileDescriptor
• Fixes issues with CFMachPort (ie. the fact the actual mach code was missing)
• Adds implementation of local, remote and Darwin notification centers
• Restored the Objective-C bridge
• Implemented (at least stubs of) Objective-C classes which are required to be found in CF

Dependencies

• libxml2 (eg from the Darwin 10.10 roots)

Building

Create a folder called "include" at the same level as this README.md (and the CoreFoundation folder) and copy into it:

• the /usr/local/include/unicode folder from your macOS system
• the mach-o folder from the dyld Darwin root
• the include folder from libxml2
• bootstrap_priv.h

TODO

• Either write a script to set up the dependencies needed for building, or switch to using the Darwin SDK
• Keep up to date with recent changes from the swift corelibs project
• Add implementation of classes from swift-corelibs-foundation
• Complete implementation of all bridged classes

Known Issues

• A crash if CFRunLoopGetCurrent() is called either before CFRunLoopGetMain() on the main thread, or at all on any other thread.