VS: Add CMakeLists.txt re-run rules at start of generation

Since commit 328c0f65 (Simplify cmVisualStudio10TargetGenerator source
classification, 2012-03-19) the VS 10 generator uses the
cmGeneratorTarget source classification instead of directly getting the
list of source files from the target.  This accidentally dropped the
CMakeLists.txt files from generated projects because they are added too
late for cmGeneratorTarget.

All generator-specific source files must be added to targets prior to
cmGeneratorTarget construction.  Refactor addition of the CMakeLists.txt
files with CMake re-run custom commands to take place before normal
generation begins, and therefore early enough to be included in the
cmGeneratorTarget classification.

Source/cmLocalVisualStudio7Generator.h

@@ -64,6 +64,7 @@ public:
 
   virtual void ReadAndStoreExternalGUID(const char* name,
                                         const char* path);
+  virtual void AddCMakeListsRules();
 protected:
   void CreateSingleVCProj(const char *lname, cmTarget &tgt);
 private: