By default cmake prefers to use shared libraries resulting in a mix of shared

and static (dune-common) linkage. For supercomputer we need pure statically 
linked binaries.

This patch maked Cmake prefer static linkage on request (i.e. setting 
DUNE_USE_ONLY_STATIC_LIB to true).

Unfortunately, this breaks the Lapack test on ubuntu and Debian (at least 
wheezy) as there are multiple definitions in libblas.a and liblapack.a.


[[Imported from SVN: r6598]]