Calm down compiler warning about unused var

Source/CPack/cmCPackDocumentMacros.cxx

@@ -3,6 +3,8 @@
 void cmCPackDocumentMacros::GetMacrosDocumentation(
         std::vector<cmDocumentationEntry>& v)
 {
+   // avoid compiler warning
+   (int)v.size();
    // Commented-out example of use
    //
    //    cmDocumentationEntry e("cpack_<macro>",

Source/CPack/cmCPackDocumentVariables.cxx

@@ -3,6 +3,8 @@
 
 void cmCPackDocumentVariables::DefineVariables(cmake* cm)
 {
+  // avoid compiler warning
+  (void*)cm;
   // Subsection: variables defined/used by cpack,
   // which are common to all CPack generators