Fix typo in ASTStructuralEquivalence.cpp for UnaryTransform types.

Previously UnaryTransformType nodes were comparing the same node
for structural equivalence. This was due to a typo where T1 was
on both sides of the comparison. This patch corrects that typo.

Unfortunately I couldn't find a way to test this change. It seems
that currently UnaryTransform nodes are never actually checked
for equivalence, only their canonical types are.

None the less, this correction seemed appropriate.

llvm-svn: 329151
diff --git a/clang/lib/AST/ASTStructuralEquivalence.cpp b/clang/lib/AST/ASTStructuralEquivalence.cpp
index a563c7e..da0a26e 100644
--- a/clang/lib/AST/ASTStructuralEquivalence.cpp
+++ b/clang/lib/AST/ASTStructuralEquivalence.cpp
@@ -501,7 +501,7 @@
   case Type::UnaryTransform:
     if (!IsStructurallyEquivalent(
             Context, cast<UnaryTransformType>(T1)->getUnderlyingType(),
-            cast<UnaryTransformType>(T1)->getUnderlyingType()))
+            cast<UnaryTransformType>(T2)->getUnderlyingType()))
       return false;
     break;