OSX/scons: change again conditional for ftemplate, it can be ambigous with xcode5, cause there is still gcc and llvm-gcc symlinks to clang, so env['CXX'] is bad test then

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk@60691 954f8c5b-7b00-dc11-b283-0030488c597c