Use "#if GTEST_HAS_DEATH_TEST" instead of "#ifdef GTEST_HAS_DEATH_TEST"

This is consistent with the rest of the GTEST_HAS_DEATH usages in
the code and the example in gtest-port.h.

PiperOrigin-RevId: 500740093
Change-Id: I2acc158116b0e8bccc8ab45d75c8059828a4c251

absl/strings/str_cat_test.cc

@@ -443,7 +443,7 @@ TEST(StrCat, AvoidsMemcpyWithNullptr) {
   EXPECT_EQ(result, "12345");
 }
 
-#ifdef GTEST_HAS_DEATH_TEST
+#if GTEST_HAS_DEATH_TEST
 TEST(StrAppend, Death) {
   std::string s = "self";
   // on linux it's "assertion", on mac it's "Assertion",

absl/strings/substitute_test.cc

@@ -265,7 +265,7 @@ TEST(SubstituteTest, AbslStringifyWithEnum) {
   EXPECT_EQ(absl::Substitute("$0", e), "Choices");
 }
 
-#ifdef GTEST_HAS_DEATH_TEST
+#if GTEST_HAS_DEATH_TEST
 
 TEST(SubstituteDeathTest, SubstituteDeath) {
   EXPECT_DEBUG_DEATH(