[ODRHash] Fix hashing for friend functions.

When hashing a templated function, use the hash of the function it was
instantiated from.

llvm-svn: 325742
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 30599ea..c4da87c 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -3625,6 +3625,12 @@
     }
   }
 
+  if (auto *FT = getInstantiatedFromMemberFunction()) {
+    HasODRHash = true;
+    ODRHash = FT->getODRHash();
+    return ODRHash;
+  }
+
   class ODRHash Hash;
   Hash.AddFunctionDecl(this);
   HasODRHash = true;