Bugfix 654: forgot to update GenerateDef

When synthesizing clauses, allow synthesised clauses to be
partial.

It's an arbitrary choice, the other choice can be the default
option. But if the place in which we're synthesising has a non-default
choice, then we're synthesising under the wrong option too.

src/TTImp/Interactive/GenerateDef.idr

@@ -56,7 +56,7 @@ expandClause : {auto c : Ref Ctxt Defs} ->
                Core (Search (List ImpClause))
 expandClause loc opts n c
     = do c <- uniqueRHS c
-         Right clause <- checkClause linear Private False n [] (MkNested []) [] c
+         Right clause <- checkClause linear Private PartialOK False n [] (MkNested []) [] c
             | Left err => noResult -- TODO: impossible clause, do something
                                    -- appropriate