When checking for the necessary 'template<>' headers based on the

When checking for the necessary 'template<>' headers based on the
nested of an out-of-line declaration, only require a 'template<>'
header for each enclosing class template that hasn't been previously
specialized; previously, we were requiring 'template<>' for enclosing
class templates and members of class templates that hadn't been
previously specialized. Fixes <rdar://problem/9422013>.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@131207 91177308-0d34-0410-b5e6-96231b3b80d8