[UnitTests] Try and pacify gcc-5

This looks like a defect in gcc-5 where it chooses a constexpr
constructor from the initializer-list that it considers to be explicit.

I've tried to reproduce but I can't install anything prior to gcc-6 easily
on my system, and that doesn't have the error. So this is speculative
pacification.

Reported by Steven Wan.

llvm-svn: 373820
diff --git a/llvm/unittests/TableGen/AutomataTest.cpp b/llvm/unittests/TableGen/AutomataTest.cpp
index 11c0342..fb19716 100644
--- a/llvm/unittests/TableGen/AutomataTest.cpp
+++ b/llvm/unittests/TableGen/AutomataTest.cpp
@@ -62,16 +62,16 @@
   Automaton<TupleAutomatonAction> A(makeArrayRef(TupleAutomatonTransitions));
   A.reset();
   EXPECT_TRUE(
-      A.add({SK_a, SK_b, "yeet"}));
+      A.add(TupleAutomatonAction{SK_a, SK_b, "yeet"}));
   A.reset();
   EXPECT_FALSE(
-      A.add({SK_a, SK_a, "yeet"}));
+      A.add(TupleAutomatonAction{SK_a, SK_a, "yeet"}));
   A.reset();
   EXPECT_FALSE(
-      A.add({SK_a, SK_b, "feet"}));
+      A.add(TupleAutomatonAction{SK_a, SK_b, "feet"}));
   A.reset();
   EXPECT_TRUE(
-      A.add({SK_b, SK_b, "foo"}));
+      A.add(TupleAutomatonAction{SK_b, SK_b, "foo"}));
 }
 
 TEST(Automata, NfaAutomatonAccepts) {