BUG: Fix crash when CMAKE_BACKWARDS_COMPATIBILITY is not set.

Source/cmGlobalGenerator.cxx

@@ -464,9 +464,7 @@ cmGlobalGenerator::EnableLanguage(std::vector<std::string>const& languages,
           // backwards compatibility files they have to load
           // These files have a bunch of try compiles in them so
           // should only be done
-          const char* versionValue
-            = mf->GetDefinition("CMAKE_BACKWARDS_COMPATIBILITY");
-          if (atof(versionValue) <= 1.4)
+          if (mf->NeedBackwardsCompatibility(1,4))
             {
             if(strcmp(lang, "C") == 0)
               {

Source/cmIncludeDirectoryCommand.cxx

@@ -50,11 +50,9 @@ bool cmIncludeDirectoryCommand
       }
     if(i->size() == 0)
       {
-      const char* versionValue =
-        this->Makefile->GetDefinition("CMAKE_BACKWARDS_COMPATIBILITY");
       const char* errorMessage
         = "Empty Include Directory Passed into INCLUDE_DIRECTORIES command.";
-      if(atof(versionValue) < 2.5)
+      if(this->Makefile->NeedBackwardsCompatibility(2,4))
         {
         cmSystemTools::Error(errorMessage);
         }