Don't use lib64 on Darwin
Don't use lib64 on Darwin

mpflanzer/Oclgrind,surround-io/oclgrind,surround-io/oclgrind,surround-io/oclgrind,mpflanzer/Oclgrind,surround-io/oclgrind,mpflanzer/Oclgrind,mpflanzer/Oclgrind