Implement NSRunLoop

[kovpas]

addPort and removePort are not implemented because NSPort implementation is missing.

[parkera]

The main issue here is that none of this will work on Linux because the CF code is not yet ported.

[kovpas]

@parkera I think I've got CFRunLoop.c working on ubuntu. Probably better to post it as a separate pull request, though. It's heavily based on CFLite by @nickhutchinson ( https://github.com/nickhutchinson/CFLite/tree/master ). Had to tweak a couple of things, but nothing too complex. Would be great if you could take a look and let me know if I could proceed with pull request.

kovpas/swift-corelibs-foundation@nsrunloop...kovpas:cfrunloop_ubuntu

[parkera]

I think you're on the right track; I had started on something similar, although I used epoll instead.

[parkera]

Since we don't really have a mechanism in our tests for writing C unit tests of CF directly, I think it makes sense to consider this all together so we can verify that it's working.

[kovpas]

@parkera makes sense to treat it as one thing, indeed. I'll update this PR. Also going to add some tests for NSTimer

One thing: for some reason NSRunLoop.swift doesn't compile for me on linux when I use CFRunLoopRunResult:

Foundation/NSRunLoop.swift:75:34: error: type of expression is ambiguous without more context
        return runloopResult == .HandledSource || runloopResult == .TimedOut
                                ~^~~~~~~~~~~~~

Do you have any idea why this could happen and how to fix that? Meanwhile I had to do that:

return runloopResult == 2 || runloopResult == 3

[parkera]

This causes a build warning:

[9/175] CompileC: closure/runtime.c
closure/runtime.c:16:9: warning: '__USE_GNU' macro redefined [-Wmacro-redefined]
#define __USE_GNU
        ^
/usr/include/features.h:322:10: note: previous definition is here
# define __USE_GNU      1
         ^
1 warning generated.

[kovpas]

It's not recommended to define __USE_GNU in code, better to use define _GNU_SOURCE. I just removed this define in closure/runtime.c, as all source files are now compiled with _GNU_SOURCE.

[parkera]

Overall looks really good. I just have a few minor comments for you to address then we'll merge this in. Thanks!