Export of internal Abseil changes

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692d3df279e7592d01c1008cb85f2a010c3d17da by Abseil Team <absl-team@google.com>:

Use EXPECT_DEATH_IF_SUPPORTED instead of raw EXPECT_DEATH.

PiperOrigin-RevId: 307802196

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ebc40936b677b79cad9f87f944794c35946f9dbd by Gennadiy Rozental <rogeeff@google.com>:

Eliminate SetCallback from absl::Flag<T> public interface.

We also make SetCallback on FlagRegistrar to return rvalue, so that we can add more tail calls after it.

PiperOrigin-RevId: 307745935
GitOrigin-RevId: 15f69a9dae9c70c884ce85ca1a4bf359a2609db0
Change-Id: Ibec13463e44e4071c48fb12389f47e716cee7a9d

absl/types/optional_test.cc

@@ -1051,7 +1051,7 @@ TEST(optionalTest, Value) {
 #ifdef ABSL_HAVE_EXCEPTIONS
   EXPECT_THROW((void)empty.value(), absl::bad_optional_access);
 #else
-  EXPECT_DEATH((void)empty.value(), "Bad optional access");
+  EXPECT_DEATH_IF_SUPPORTED((void)empty.value(), "Bad optional access");
 #endif
 
   // test constexpr value()

absl/types/variant_test.cc

@@ -50,7 +50,7 @@
 #else
 
 #define ABSL_VARIANT_TEST_EXPECT_FAIL(expr, exception_t, text) \
-  EXPECT_DEATH(expr, text)
+  EXPECT_DEATH_IF_SUPPORTED(expr, text)
 
 #endif  // ABSL_HAVE_EXCEPTIONS