From Jan Klimke, "i noticed, that there are a couple of additional flaws when building osg for Mac OS X 10.10 Yosemite.
The mac os sdk version is recognized by the current CMAKE script as 10.1 instead of 10.10 since it cuts the version string from the 4th place. I introduced a more reliable version checking based on splitting the returned version code into MAJOR MINOR and PATCH parts and reassemble the OSG sdk version afterwards.
I replaced the existing CMake code against the following (returning now version 10.10 as expected):
# Determine the canonical name of the selected Platform SDK
Also i added the check for the new Version to some more find scripts.
Additionally the nil object in Objective C now seems to be equivalent with a null_ptr that cannot be passed as GLInt anymore. So i switched this in the PixelBufferCocoa?.mm to pass a zero instead of nil.