Added #error for Carbon + OS X 10.7 SDK

Some of the functions used by the Carbon render window
are so old that they don't even exist in 10.7 SDK.
Added #error to catch this.

Change-Id: Ib5694a127cd59148f4ed2123d76d63f62ccc9b61
Fix Carbon build with newer Xcodes

We were trying to find Rez in the old hardcoded /Developer
folder.  Instead, now use OSX_DEVELOPER_ROOT.

Change-Id: Ie2f337c45f14bb585ccafa78e9a4414a0d17999a
Fixed Carbon build error due to modularization changes.

Fix from David Gobbi brought over from python case.

Change-Id: Ibba401173eb817be7dda1215aeec586b3b4b82f1
Merge topic 'carbon-fix' into master

2297e5db Fixed Carbon build error due to modularization changes.
02d783e7 Fix Carbon build with newer Xcodes
caf4fcac Added #error for Carbon + OS X 10.7 SDK