Zoltan expects mpi libraries with option --with-mpi-libs.
If this option is not provided then it uses '-lmpi' which
may not be correct. To avoid this, we have to explicitly
pass empty string.
This adds notes to the source explaining the change.
* Refactored and reorganized the 'zoltan' install script.
* Fixed a few bugs with the '+mpi' and '+fortan' variants of 'zoltan'.
* Reintroduced and improved the '+shared' variant for the 'zoltan' package.
* Improved compatibility with different MPI providers for 'zoltan'.
* Added preliminary implementations for the debug and shared variants.
* Fixed a few problems with the '+shared' variant of the Zoltan package.
Added support for a few more important Zoltan package versions.
* Fixed a minor compiler incompatibility issue with the '+shared+mpi' variants.
