Apply patch from Richard Trieu to fix PR9548:

When two different types has the same text representation in the same
diagnostic message, print an a.k.a. after the type if the a.k.a. gives extra
information about the type.

class versa_string;

typedef versa_string string;

namespace std {template <typename T> class vector;}

using std::vector;

void f(vector<string> v);

namespace std {
class basic_string;
typedef basic_string string;
template <typename T> class vector {};
void g() {
  vector<string> v;
  f(v);
}
}

Old message:
----------------
test.cc:15:3: error: no matching function for call to 'f'
  f(&v);
  ^
test.cc:7:6: note: candidate function not viable: no known conversion from
      'vector<string>' to 'vector<string>' for 1st argument
void f(vector<string> v);
     ^
1 error generated.

New message:
---------------
test.cc:15:3: error: no matching function for call to 'f'
  f(v);
  ^
test.cc:7:6: note: candidate function not viable: no known conversion from
      'vector<string>' (aka 'std::vector<std::basic_string>') to
      'vector<string>' (aka 'std::vector<versa_string>') for 1st argument
void f(vector<string> v);
     ^
1 error generated.

llvm-svn: 134904