MFC r261680:

Pull in r200899 from upstream clang trunk:

  Allow transformation of VariableArray to ConstantArray.

  In the following code:

     struct A { static const int sz; };
     template<class T> void f() { T arr[A::sz]; }

  the array 'arr' is represented as a variable size array in the template.
  If 'A::sz' gets value below in the translation unit, the array in
  instantiation can turn into constant size array.

  This change fixes PR18633.

  Differential Revision: http://llvm-reviews.chandlerc.com/D2688

This fixes "Assertion failed: (T::isKind(*this)), function castAs"
errors, which can occur when building the security/quantis port.

Reported by:	ale