review: move recomputeHeader to common point

llvm/lib/ObjCopy/DXContainer/DXContainerObjcopy.cpp

@@ -31,6 +31,7 @@ static Error handleArgs(const CommonConfig &Config, Object &Obj) {
   if (auto E = Obj.removeParts(RemovePred))
     return E;
 
+  Obj.recomputeHeader();
   return Error::success();
 }
 

llvm/lib/ObjCopy/DXContainer/DXContainerObject.cpp

@@ -14,7 +14,6 @@ namespace dxbc {
 
 Error Object::removeParts(PartPred ToRemove) {
   erase_if(Parts, ToRemove);
-  recomputeHeader();
   return Error::success();
 }
 

llvm/lib/ObjCopy/DXContainer/DXContainerObject.h

@@ -42,8 +42,6 @@ struct Object {
   }
 
   Error removeParts(PartPred ToRemove);
-
-private:
   void recomputeHeader();
 };