* root: new versions, variants and patches to bring in to line with FNAL's use.
* Support MySQL.
* Patches:
* Bigger stringbuf.
* Find MySQL even when it's called mariadb-c-client.
* Honor external provision of unuran.
* Properly handle the ROOT7 web GUI for 6.16/00.
* `memstat` variant is now default-OFF due to version-related constraints.
* Add missing dependencies.
* Propagate `python` to `libxml2`.
* Handle external FTGL dependency with X / OpenGL: depends on PR ####
* Force `SPACK_INCLUDE_DIRS` to avoid warning.
* New `gminimal` variant default ON per discussion with Javier Cervantes.
* Style fixes per flake8.
* Remove redundant `PATH_SUFFIX` per https://github.com/root-project/root/pull/1993#discussion_r276840329
* Comment patches per https://github.com/spack/spack/pull/11215#discussion_r276887199.
* Reflect the fact that MariaDB support patch is now upstream.
* Restore ncurses dependency for libtinfo.
