Merge pull request mapnik#2879 from zerebubuth/fix/remove-unused-source-files

Remove unused source `memory.[ch]pp`.

Author: artemp

include/mapnik/memory.hpp

@@ -192,7 +192,6 @@ def ldconfig(*args,**kwargs):
     layer.cpp
     map.cpp
     load_map.cpp
-    memory.cpp
     palette.cpp
     marker_helpers.cpp
     transform_expression_grammar.cpp