Fix/Improve displayed build system information #46
Description
As an example, the Silo package is now a dual-build-system package (autotools and cmake). But, the page for Silo shows only autotools and autotools is deprecated in 4.12.0 and will no longer be available in versions after 4.12.0.
I went looking for the code that generates the html for the build-system piece of the package's pages and did not understand fully what I was looking at.
There is, for example a loop over the list of maintainters to list maintainers and I was thinking I could do the same for the build system but I could not locate the necessary logic in generate_pacages.py. The logic that controls this may be in spack proper in terms of what it returns for the build_system_class member.
For a package with multiple build systems, it might be nice to include the list of those and versions of package to which they apply and then also what the default build system is set to.
I'll post an image of Silo's page...
