Ninja: Add support for OX X library framework.

This patch fixes test ExportImport on Darwin.

Source/cmNinjaNormalTargetGenerator.h

@@ -35,6 +35,7 @@ private:
   void WriteObjectLibStatement();
   std::vector<std::string> ComputeLinkCmd();
   void CreateAppBundle(const std::string& targetName, std::string& outpath);
+  void CreateFramework(std::string const& targetName);
 
 private:
   // Target name info.
@@ -45,6 +46,7 @@ private:
   std::string TargetNamePDB;
   const char *TargetLinkLanguage;
   std::string MacContentDirectory;
+  std::string FrameworkVersion;
 };
 
 #endif // ! cmNinjaNormalTargetGenerator_h