When computing the template arguments for the instantiation of a

When computing the template arguments for the instantiation of a
friend function template, be sure to adjust the computed template
argument lists based on the location of the definition of the function
template: it's possible that the definition we're instantiating with
and the template declaration that we found when creating the
specialization are in different contexts, which meant that we would
end up using the wrong template arguments for instantiation.

Fixes PR7013; all Boost.DynamicBitset tests now pass.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@102974 91177308-0d34-0410-b5e6-96231b3b80d8