Sean McBride's Darwin patch

[Xiaofan Chen]

Sean McBride posted the following patches for Darwin.
http://libusb.6.n5.nabble.com/PATCHES-thread-safety-on-darwin-and-minor-other-changes-tp5062714p5062714.html

Nathan acked the first 4 patches.
http://libusb.6.n5.nabble.com/PATCHES-thread-safety-on-darwin-and-minor-other-changes-tp5062714p5073472.html

Only the first patch is in libusb.git/libusbx.git. Probably the other three
patches should be integrated as well.

BTW, is Sean in the mailing list?

-- 
Xiaofan