Don't build finite-strain-elasticity w. dune-common 2.7 & dune-fufem 2.8

Because in this particular combination, no cmake Python test is ever
called, and therefore Python is not available.

src/CMakeLists.txt

 if(ADOLC_FOUND AND IPOPT_FOUND AND PYTHONLIBS_FOUND AND dune-uggrid_FOUND)
-  set(programs finite-strain-elasticity
-               linear-elasticity)
+  set(programs linear-elasticity)
+
+  # When combining dune-common 2.7 and dune-fufem 2.8, no cmake test for the
+  # Python bindings is ever called (that's not a bug).  In that case
+  # we simply skip building the one executable that needs Python.
+  if(NOT (${dune-common_VERSION} VERSION_LESS_EQUAL "2.7.9" AND ${dune-fufem_VERSION} VERSION_GREATER_EQUAL "2.8.0"))
+    set(programs ${programs} finite-strain-elasticity)
+  endif()
 
   foreach(_program ${programs})
     add_executable(${_program} ${_program}.cc)