CHG: switch MacOS test builds to MacPorts gcc 4.8 from 4.7


git-svn-id: https://www.nitrc.org/svn/cmtk/trunk@5075 42a5c34f-2066-0410-bec5-ba365beb4995
DOC


git-svn-id: https://www.nitrc.org/svn/cmtk/trunk@5076 42a5c34f-2066-0410-bec5-ba365beb4995