* libunwind: remove version 2018.10.12, add stable branch
Finish cleaning up the libunwind version numbers. The 2018.10.12
snapshot number didn't fit well with spack's ordering (my bad), and
1.4-rc1 is a near identical replacement.
Add a version for the 1.4-stable branch.
Add a variant for zlib compressed symbol tables (develop branch only).
Adjust packages caliper and hpctoolkit to adapt to the changes.
Add myself as maintainer.
* Flake
* Settle on renaming 'develop' to 'master' (to match the branch name)
and name the 'v1.4-stable' branch as '1.4-head'. 'stable' or
'1.4-stable' is a better name, but '1.4-head' (an infinity version)
sorts better.
441340771d