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/time/internal/cctz/src/time_zone_impl.cc

@@ -20,9 +20,11 @@
 #include <unordered_map>
 #include <utility>
 
+#include "absl/base/config.h"
 #include "time_zone_fixed.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace time_internal {
 namespace cctz {
 
@@ -43,9 +45,7 @@ std::mutex& TimeZoneMutex() {
 
 }  // namespace
 
-time_zone time_zone::Impl::UTC() {
-  return time_zone(UTCImpl());
-}
+time_zone time_zone::Impl::UTC() { return time_zone(UTCImpl()); }
 
 bool time_zone::Impl::LoadTimeZone(const std::string& name, time_zone* tz) {
   const time_zone::Impl* const utc_impl = UTCImpl();
@@ -117,4 +117,5 @@ const time_zone::Impl* time_zone::Impl::UTCImpl() {
 
 }  // namespace cctz
 }  // namespace time_internal
+ABSL_NAMESPACE_END
 }  // namespace absl