flux: update flux-core to v0.8.0 (#5914)

* dockbook: remove update to dependent environment

Remove override of setup_dependent_environment in both docbook-xml
and docbook-xsl, which seems to generate a warning from spack about
"Suspicious requests to set or unset 'XML_CATLOG_FILES' found."

* flux: update version/dependencies to 0.8.0

Update flux-core to v0.8.0. Clean up dependencies and remove unneeded
extra invocation of ./autogen.sh when building from @master.

* flux: modify environment for Lua tests

Modify Spack environment to add `./?.lua` to LUA_PATH so that
fluxometer.lua can be found by tests during `make check` run
from `spack install --tests all flux`

* flux: fix broken flux version when on master

When building @master with spack, the flux version test from
`make check` fails because spack is using a shallow clone. Add
a setup section for @master that calls git pull --depth=50 --tags
to pull down tags and (hopefully) enough information for git-describe
to work properly.

var/spack/repos/builtin/packages/docbook-xml/package.py

@@ -42,10 +42,6 @@ def install(self, spec, prefix):
             else:
                 install(src, dst)
 
-    def setup_dependent_environment(self, spack_env, run_env, dependent_spec):
-        catalog = os.path.join(self.spec.prefix, 'catalog.xml')
-        spack_env.set('XML_CATALOG_FILES', catalog, separator=' ')
-
     def setup_environment(self, spack_env, run_env):
         catalog = os.path.join(self.spec.prefix, 'catalog.xml')
         run_env.set('XML_CATALOG_FILES', catalog, separator=' ')