Export of internal Abseil changes

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20b3acaff75d05315f272747956b01405adccafb by Greg Falcon <gfalcon@google.com>:

Re-import of CCTZ from GitHub, with new ABSL_NAMESPACE_ transform applied.

PiperOrigin-RevId: 285564474

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4d9e3fcabcea33c8b0b69f094ad2eddc0fa19557 by Derek Mauro <dmauro@google.com>:

Moves the disabling of a warning to before the function begins.

MSVC apparently requires this for warnings in the range 4700-4999.
https://docs.microsoft.com/en-us/cpp/preprocessor/warning?redirectedfrom=MSDN&view=vs-2019

PiperOrigin-RevId: 285516232

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4a060cbeda76e89693c50276ae5b62cbf0fff39a by Derek Mauro <dmauro@google.com>:

MSVC: Fixes uniform_real_distribution_test in opt mode

Disables a constant arithmetic overflow warning in a test that tests
the behavior on overflow. This should be tested because a user might
have this warning disabled.

PiperOrigin-RevId: 285452242

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548ab2f4cbe59bd6f6bf493af4f9ea765c4fa949 by Andy Soffer <asoffer@google.com>:

Release absl::bind_front, a C++11-compliant work-alike type for the C++20
std::bind_front.

PiperOrigin-RevId: 285247872
GitOrigin-RevId: 20b3acaff75d05315f272747956b01405adccafb
Change-Id: I00fe45939246cba9bfc7be375d67787d2eb57cd3

absl/random/uniform_real_distribution_test.cc

@@ -161,6 +161,10 @@ TYPED_TEST(UniformRealDistributionTest, ParamSerializeTest) {
   }
 }
 
+#ifdef _MSC_VER
+#pragma warning(push)
+#pragma warning(disable:4756)  // Constant arithmetic overflow.
+#endif
 TYPED_TEST(UniformRealDistributionTest, ViolatesPreconditionsDeathTest) {
 #if GTEST_HAS_DEATH_TEST
   // Hi < Lo
@@ -195,6 +199,9 @@ TYPED_TEST(UniformRealDistributionTest, ViolatesPreconditionsDeathTest) {
   }
 #endif  // NDEBUG
 }
+#ifdef _MSC_VER
+#pragma warning(pop)  // warning(disable:4756)
+#endif
 
 TYPED_TEST(UniformRealDistributionTest, TestMoments) {
   constexpr int kSize = 1000000;