// and their values, as strings.  For example, for ASSERT_EQ(foo, bar)
// where foo is 5 and bar is 6, we have:
//
//   expected_expression: "foo"
//   actual_expression:   "bar"
//   expected_value:      "5"
//   actual_value:        "6"
//
// The ignoring_case parameter is true iff the assertion is a
// *_STRCASEEQ*.  When it's true, the string " (ignoring case)" will
// be inserted into the message.