Incorrect order of base-class initializers in class template [GH #302]

[nv-cmeerw]

Fixes #302

Incorrect order of base-class initializers in class template

Previously, in the IL for prototype instantiations of class templates,
base-class mem-initializers with non-type template arguments could appear after
the initializers for other base classes. Such initializers are now recorded in
base-class declaration order when the base class can be identified.
Initializers for base classes that cannot yet be identified now retain their
source order relative to the next initializer for an identified nonvirtual
direct base class. For example, with --c++11:

  template<int> struct A { };
  struct B { };
  template<int N> struct C : A<N>, B {
    C() : A<N>(), B() { }      // Previously recorded as "B(), A<N>()".
    C(int) : A<+N>(), B() { }  // Previously recorded as "B(), A<+N>()".
  };

Both initializer lists are now recorded in the order shown.