Merging r286584:

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r286584 | abataev | 2016-11-11 12:36:20 +0000 (Fri, 11 Nov 2016) | 31 lines

Fix for PR28523: unexpected compilation error.

Clang emits error message for the following code:
```
template <class F> void parallel_loop(F &&f) { f(0); }

int main() {
  int x;
  parallel_loop([&](auto y) {
    {
      x = y;
    };
  });
}
```

$ clang++ --std=gnu++14 clang_test.cc -o clang_test
clang_test.cc:9:7: error: reference to local variable 'x' declared in enclosing function 'main'
      x = y;
            ^
clang_test.cc:2:48: note: in instantiation of function template specialization 'main()::(anonymous class)::operator()<int>' requested here
            template <class F> void parallel_loop(F &&f) { f(0); }
                                                           ^
clang_test.cc:6:3: note: in instantiation of function template specialization 'parallel_loop<(lambda at clang_test.cc:6:17)>' requested here parallel_loop([&](auto y) {
           ^
clang_test.cc:5:7: note: 'x' declared here
      int x;
          ^
1 error generated.

Patch fixes this issue.
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git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_39@286966 91177308-0d34-0410-b5e6-96231b3b80d8