ENH: Hardened GDALOverviewsBuilder::CountResolutions().

Modules/IO/IOGDAL/src/otbGDALOverviewsBuilder.cxx

@@ -108,14 +108,17 @@ GDALOverviewsBuilder
 
   unsigned int minSize = static_cast< unsigned int >( pow( factor, n ) );
 
-  unsigned int count = 1;
-
   unsigned int size =
     std::min(
       m_GdalDataset->GetWidth(),
       m_GdalDataset->GetHeight()
     );
 
+  if( size<minSize )
+    return 0;
+
+  unsigned int count = 0;
+
   while( size >= minSize )
     {
     ++ count;