Prep for merging 3.4: Undo changes from 3.3 branch

test/SemaCXX/cxx11-inheriting-ctors.cpp

-// RUN: %clang_cc1 -std=c++11 %s -verify
-
-// expected-no-diagnostics
-
-namespace PR15757 {
-  struct S {
-  };
-
-  template<typename X, typename Y> struct T {
-    template<typename A> T(X x, A &&a) {}
-
-    template<typename A> explicit T(A &&a)
-        noexcept(noexcept(T(X(), static_cast<A &&>(a))))
-      : T(X(), static_cast<A &&>(a)) {}
-  };
-
-  template<typename X, typename Y> struct U : T<X, Y> {
-    using T<X, Y>::T;
-  };
-
-  U<S, char> foo(char ch) { return U<S, char>(ch); }
-
-  int main() {
-    U<S, int> a(42);
-    U<S, char> b('4');
-    return 0;
-  }
-}