cmMakefile: Avoid invoking EnforceDirectoryLevelRules.

This is part of the CMP0000 implementation and only needs to be invoked
for top-level buildsystem files currently.

Source/cmGlobalGenerator.cxx

@@ -1106,6 +1106,7 @@ void cmGlobalGenerator::Configure()
 
   // now do it
   lg->GetMakefile()->Configure();
+  lg->GetMakefile()->EnforceDirectoryLevelRules();
 
   // update the cache entry for the number of local generators, this is used
   // for progress

Source/cmMakefile.cxx

@@ -445,7 +445,6 @@ bool cmMakefile::ProcessBuildsystemFile(const char* filename)
     {
     scope.Quiet();
     }
-  this->EnforceDirectoryLevelRules();
   return true;
 }
 

Source/cmMakefile.h

@@ -825,6 +825,8 @@ public:
 
   std::string GetExecutionFilePath() const;
 
+  void EnforceDirectoryLevelRules() const;
+
 protected:
   // add link libraries and directories to the target
   void AddGlobalLinkInformation(const std::string& name, cmTarget& target);
@@ -975,9 +977,6 @@ private:
   cmPolicies::PolicyStatus
   GetPolicyStatusInternal(cmPolicies::PolicyID id) const;
 
-  // Enforce rules about CMakeLists.txt files.
-  void EnforceDirectoryLevelRules() const;
-
   // CMP0053 == old
   cmake::MessageType ExpandVariablesInStringOld(
                                   std::string& errorstr,