Build all executables unconditionally

Building them only when all required dependencies are there
just means that I don't get meaningful error messages.

src/CMakeLists.txt

-if(ADOLC_FOUND AND IPOPT_FOUND AND PYTHONLIBS_FOUND AND dune-uggrid_FOUND)
   set(programs finite-strain-elasticity
                linear-elasticity
                quasiconvexity-test
@@ -23,5 +22,4 @@ if(ADOLC_FOUND AND IPOPT_FOUND AND PYTHONLIBS_FOUND AND dune-uggrid_FOUND)
   if (PSURFACE_FOUND)
     add_dune_psurface_flags(linear-elasticity)
   endif()
-endif()