BUG: Fix/cleanup custom commands and custom targets. Make empty comment strings work. Fix ZERO_CHECK target always out of date for debugging. Fix Makefile driving of custom commands in a custom target. Fix dependencies on custom targets not in ALL in VS generators.

Source/cmMakefileTargetGenerator.h

@@ -107,6 +107,8 @@ protected:
   // write the driver rule to build target outputs
   void WriteTargetDriverRule(const char* main_output, bool relink);
 
+  void DriveCustomCommands(std::vector<std::string>& depends);
+
   // Return the a string with -F flags on apple
   std::string GetFrameworkFlags();
 
@@ -122,6 +124,8 @@ protected:
   cmGlobalGenerator *GlobalGenerator;
   cmMakefile *Makefile;
 
+  bool DriveCustomCommandsOnDepends;
+
   // the full path to the build file
   std::string BuildFileName;
   std::string BuildFileNameFull;