Merge branch 'fix/install-superlufunctions' into 'master'

[CMake] install superlufunctions.hh

superlufunctions.hh which was introduced in !77 has to be installed as it is included by the installed headers superlu.hh and supermatrix.hh.

See merge request !78

dune/istl/CMakeLists.txt

@@ -42,6 +42,7 @@ install(FILES
    solvertype.hh
    spqr.hh
    superlu.hh
+   superlufunctions.hh
    supermatrix.hh
    umfpack.hh
    vbvector.hh