Mumps is a sparse linear solver, and could be used for other problems
besides numerical optimization.

Robotpkg must look for sequential implementation libraries of
Mumps. They are suffixed with _seq.

- Fix patch-ab for the F_ARITH_SYMBOL definition
- Add patch-ac fixing mumps_elapse symbol name definition
- Suffix libraries with _seq, as we build only the sequential version (no MPI).
- Add version tag to dso
- Require gcc-fortran>=4 (f90 compiler).

Add configure/Makefile scripts, and try to make this robust.
This needs testing.