tests: Adjust expectations in accordance with -DNDEBUG

If assertions are disabled then `EXPECT_DEATH()` will fail. Guard
`EXPECT_DEATH()` calls with an NDEBUG test, and substitute an
appropriate test when it's defined.

Change-Id: I60541762aceb656c2eff03a438f314197b281f77
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
diff --git a/tests/libpldm_firmware_update_test.cpp b/tests/libpldm_firmware_update_test.cpp
index 493da65..c42381c 100644
--- a/tests/libpldm_firmware_update_test.cpp
+++ b/tests/libpldm_firmware_update_test.cpp
@@ -1608,12 +1608,19 @@
      *  The 1st parameter is the function under test.
      *  The 2nd parameter compares the output of the program.
      */
-    ASSERT_DEATH(
+#ifdef NDEBUG
+    EXPECT_NE(decode_query_downstream_identifiers_resp(
+                  response, responseMsg.size() - hdrSize, &resp_data,
+                  &downstreamDevices),
+              PLDM_SUCCESS);
+#else
+    EXPECT_DEATH(
         decode_query_downstream_identifiers_resp(
             response, responseMsg.size() - hdrSize, &resp_data,
             &downstreamDevices),
         // This error doesn't output any error message, leave it be empty
         "");
+#endif
 }
 
 TEST(QueryDownstreamIdentifiers, decodeRequestErrorBufSize)