Draft: Demonstrate how Jed's gmakegen.py can be used to build other PETSc dependent...

Demonstrate how Jed's gmakegen.py can be used to build other PETSc dependent packages at the same time as PETSc

without using the other packages compiler system putting results into the PETSc libraries.

Rough prototype with --download-slepc This would allow code in PETSc to have dependencies on SLEPc and not do crazy dynamic linking nonsense

can be done with permon bamg and possibly other packages.

I mentioned this at the last PETSc Zoom meeting; this kind of approach would open up a lot of doors for parts of PETSc code to depend on other people's PETSc based packages in a trivial manner.