[Dune] UG linker error - fixed

[lriedel at iup.uni-heidelberg.de]

Hi Christoph,

As i previously had no clue about the CMake build system i just copied
stuff from the other Dune modules. You were correct, this probably messed
things up.
I got the error fixed by studying the CMakeLists.txt files in the
dune-pdelab-howto project - which had no problem with compiling and
linking - and adding appropriate lines to the ones of my project - which
uses PDELab, by the way.

The CMakeLists.txt of my project's src/ folder looks like this now:

set(noinst_PROGRAMS <my program>)
set(noinst_HEADERS <header files>)
add_executable(<my program> <my program>.cc)
add_dune_ug_flags(<my program>)
add_dune_mpi_flags(<my program>)
target_link_libraries(<my program> ${DUNE_LIBS})
add_dune_superlu_flags(<my program>)

Anyway, thank you again.
Cheers,
Lukas