Make filesytem more resilient to concurrent updates.
Make filesytem more resilient to concurrent updates.

- Uses O_CREAT for touch (for guaranteed atomic open on NFS, multi-node)
- Ignore concurrent create errors in mkdirp

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