Slightly more robust tmp directory search.
Slightly more robust tmp directory search.

- remove getcwd() check (seems arbitrary -- if users set their TMPDIR
  to this why stop them?)

- try a number of common locations and try per-user directories in
  them first.

krafczyk/spack,skosukhin/spack,tmerrick1/spack,LLNL/spack,tmerrick1/spack,EmreAtes/spack,EmreAtes/spack,skosukhin/spack,lgarren/spack,matthiasdiener/spack,mfherbst/spack,EmreAtes/spack,iulian787/spack,iulian787/spack,matthiasdiener/spack,krafczyk/spack,krafczyk/spack,mfherbst/spack,krafczyk/spack,LLNL/spack,tmerrick1/spack,krafczyk/spack,lgarren/spack,LLNL/spack,LLNL/spack,EmreAtes/spack,lgarren/spack,mfherbst/spack,TheTimmy/spack,TheTimmy/spack,TheTimmy/spack,matthiasdiener/spack,skosukhin/spack,EmreAtes/spack,iulian787/spack,matthiasdiener/spack,tmerrick1/spack,LLNL/spack,iulian787/spack,mfherbst/spack,iulian787/spack,TheTimmy/spack,matthiasdiener/spack,mfherbst/spack,TheTimmy/spack,skosukhin/spack,skosukhin/spack,lgarren/spack,tmerrick1/spack,lgarren/spack