GitLab

- libfabric-1.8.1 available in spack
- mobject needs different ssg than margo tests.  put mobject tests on hold

- file backend could have different dependencies

- default 1 second, each direction, before measurements

- default to 100

- may need some tweaks to confirm/correct which interface is used

- match current style on cooley and bebop
- set explicit HOME to avoid interference from user spack env

- must build benchmarks twice, once with pmdk back end and once with
  file backend
- rpath in executable keeps a fixed library linkage otherwise