STYLE: improve wmkdepend parse error message

- parsing error state only arises from a missing final newline
  in the file (which the dnl macro does not capture).
  Report with a warning instead of modifying the dnl macro since
  we generally wish to know about this anyhow.

- add missing newline to YEqn.H file.

applications/solvers/combustion/chemFoam/YEqn.H

@@ -9,4 +9,4 @@
             mesh.solver("Yi")
         );
     }
-}
+}