workaround to successfully detect presense of attr/xattr.h
workaround to successfully detect presense of attr/xattr.h

trshaffer/cvmfs,djw8605/cvmfs,reneme/cvmfs,djw8605/cvmfs,alhowaidi/cvmfsNDN,cvmfs/cvmfs,alhowaidi/cvmfsNDN,Moliholy/cvmfs,cvmfs-testing/cvmfs,reneme/cvmfs,djw8605/cvmfs,cvmfs-testing/cvmfs,cvmfs-testing/cvmfs,Gangbiao/cvmfs,cvmfs-testing/cvmfs,MicBrain/cvmfs,Moliholy/cvmfs,DrDaveD/cvmfs,MicBrain/cvmfs,cvmfs/cvmfs,DrDaveD/cvmfs,cvmfs-testing/cvmfs,trshaffer/cvmfs,Moliholy/cvmfs,trshaffer/cvmfs,djw8605/cvmfs,MicBrain/cvmfs,cvmfs/cvmfs,DrDaveD/cvmfs,Moliholy/cvmfs,DrDaveD/cvmfs,MicBrain/cvmfs,Gangbiao/cvmfs,DrDaveD/cvmfs,alhowaidi/cvmfsNDN,cvmfs/cvmfs,alhowaidi/cvmfsNDN,Gangbiao/cvmfs,cvmfs/cvmfs,trshaffer/cvmfs,reneme/cvmfs,alhowaidi/cvmfsNDN,djw8605/cvmfs,Moliholy/cvmfs,reneme/cvmfs,Gangbiao/cvmfs,MicBrain/cvmfs,cvmfs/cvmfs,DrDaveD/cvmfs,trshaffer/cvmfs,DrDaveD/cvmfs,Gangbiao/cvmfs,reneme/cvmfs,cvmfs/cvmfs