ENH: make sure path is converted to unix

Source/cmIncludeExternalMSProjectCommand.cxx

@@ -42,13 +42,14 @@ bool cmIncludeExternalMSProjectCommand::InitialPass(std::vector<std::string> con
     std::string utility_name("INCLUDE_EXTERNAL_MSPROJECT");
     utility_name += "_";
     utility_name += args[0];
-
+    std::string path = args[1];
+    cmSystemTools::ConvertToUnixSlashes(path);
     const char* no_output = 0;
     const char* no_working_directory = 0;
     this->Makefile->AddUtilityCommand(utility_name.c_str(), true,
                                   no_output, depends,
                                   no_working_directory,
-                                  args[0].c_str(), args[1].c_str());
+                                  args[0].c_str(), path.c_str());
     
     }
 #endif