cmake: Remove unused cmPolicies member.

heaptrack showed a 1 byte allocation with the backtrace pointing
here, as is the case since commit v3.3.0-rc1~112^2~5 (cmPolicies:
Remove unused cmPolicy class., 2015-05-03)

Source/cmake.cxx

@@ -133,7 +133,6 @@ cmake::cmake()
   this->ClearBuildSystem = false;
   this->FileComparison = new cmFileTimeComparison;
 
-  this->Policies = new cmPolicies();
   this->State = new cmState(this);
   this->CurrentSnapshot = this->State->CreateBaseSnapshot();
 
@@ -171,7 +170,6 @@ cmake::cmake()
 cmake::~cmake()
 {
   delete this->CacheManager;
-  delete this->Policies;
   delete this->State;
   if (this->GlobalGenerator)
     {

Source/cmake.h

@@ -27,7 +27,6 @@ class cmVariableWatch;
 class cmFileTimeComparison;
 class cmExternalMakefileProjectGenerator;
 class cmDocumentationSection;
-class cmPolicies;
 class cmTarget;
 class cmGeneratedFileStream;
 
@@ -340,7 +339,6 @@ protected:
   void AddExtraGenerator(const std::string& name,
                          CreateExtraGeneratorFunctionType newFunction);
 
-  cmPolicies *Policies;
   cmGlobalGenerator *GlobalGenerator;
   cmCacheManager *CacheManager;
   std::map<std::string, WarningLevel> WarningLevels;