Add initializer list to hidl_vec.

Test: libhidl_test
Change-Id: I7f25fee84feed31c3f84ca640156c0befea1d2c7
diff --git a/test/main.cpp b/test/main.cpp
index f5b5f20..a7dc243 100644
--- a/test/main.cpp
+++ b/test/main.cpp
@@ -89,6 +89,10 @@
 
     vector<int32_t> v2 = hv1; // cast
     EXPECT_ARRAYEQ(v2, v, 3);
+
+    hidl_vec<int32_t> v3 = {5, 6, 7}; // initializer_list
+    EXPECT_EQ(v3.size(), 3);
+    EXPECT_ARRAYEQ(v3, array, v3.size());
 }
 
 TEST_F(LibHidlTest, TaskRunnerTest) {