[fmatrixtest] Drop dummy.f.

I have no idea why fmatrixtest compiled and linked dummy.f, and it made compilation fail in the absence of gfortran.

[DONE] Check that linking against a static liblapack still works. (fmatrixtest simply does not seem to need lapack)

Planned merge: 2016-11-26

dune/common/test/CMakeLists.txt

@@ -90,8 +90,7 @@ dune_add_test(SOURCES densevectortest.cc
 
 dune_add_test(SOURCES enumsettest.cc)
 
-dune_add_test(NAME fmatrixtest
-              SOURCES fmatrixtest.cc dummy.f
+dune_add_test(SOURCES fmatrixtest.cc
               LINK_LIBRARIES dunecommon)
 add_dune_vc_flags(fmatrixtest)