Patches for Yosemite

This gets rippled going on Yosemite.

After upgrading you have to re-install command-line tools prior to building:
$ xcode-select --install

Tested on both Mavericks and Yosemite.  Passes Travis.
@josh-ripple @niq
I can do that.  But does anyone give a warning or anything?  #undef on something that isn't defined isn't an error.  Adding the #ifdef will just add noise unless it actually fixes something bad.
https://ideone.com/mGsa7f