IncludeCleaner: false positive with templates inheriting members

[sam-mccall]

// main.cc
#include "derived.h" // erroneously marked as unused
class Holder {
  void foo() { Member.base(); } // bug goes away if this is missing!
  Derived<0> Member;
};

// derived.h
#pragma once
#include "base.h"
template <int> struct Derived : Base {};

// base.h
struct Base { void base(); }; 

[sam-mccall]

(This is reduced from examples in LLVM: derived is StringSet and base is StringMap{Impl})

[kirillbobyrev]

Thanks a lot!