This improves the documentation for `spack external find` in several ways:
* Provide a code example of implementing `determine_spec_details` for a package
* Explain how to define executables to look for (and also e.g. that they are treated as regular expressions and so can pull in unexpected files).
* Add the "why" for a couple of constraints (i.e. explain that this logic only works for build/run deps because it examines `PATH` for executables)
* Spread the docs between build customization and packaging sections
* Add cross-references
* Add a label so that `spack external find` is linked from the command reference.
Modifications:
- [x] Travis now uses `bionic` as a default (`xenial` used for Python 3.5, `trusty` for Python 2.6)
- [x] Shell unit tests have been factored into their own run
- [x] `kcov` is built only for tests that upload coverage results
Overall with this we shave 3-4 mins. on each run and add an additional run of about 3 min. For some reason `kcov` 38 fails forwarding output when used with Python unit tests, so I used v34 for that and v38 (latest) for shell testing. Previously we were using v25.
-[x] `z3` needs a dependency on `py-setuptools`
-[x] `z3` has a run dependency on `python`, so we might as well make
building with the python bindings default
`clingo` has some undocumented dependencies:
- `bison`, for which the default macos version is too old
- `re2c`, which isn't always available
Also, the python installation was not set up properly. Clingo by default
does an install in `~/.local`, so we need to disable that and add a few
other options to get things right.
- [x] add `bison` dependency
- [x] add `re2c` dependency
- [x] make `doxygen` dependency optional (and patch if needed)
- [x] add options to fix `python` build
- [x] make python build optional but on by default
* Add pmi support (required by ucx, ofi, and gni backends)
* Add support for ucx backend
* Add dependency on MPI for pmi=simplepmi, slurmpmi, or slurmpmi2
* Remove charmpp as an MPI provider since the changes in this PR can
add MPI as a dependency (mentioned previously)
* Install into transport_protocol-OS-arch subdirectory to match
default charmpp installation behavior (which helps dependents find it)
SKX includes AVX-512 extensions that consumer Skylake processors do
not have. Therefore, map Skylake to the prior arch to work on
these systems. Skylake-X processors will still map as the
skylake_avx512 spack arch and get the correct optimzations.
