Export of internal Abseil changes

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91ca367a7548270155721bdda74611aeea2a2153 by Abseil Team <absl-team@google.com>:

Replace the only usage of btree_node::swap with simpler logic using transfers and delete btree_node::swap.

Add a benchmark for constructing small containers.

PiperOrigin-RevId: 301169874

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ff9d73a7125b7f8ab5733cda877204dfbfac138e by Derek Mauro <dmauro@google.com>:

Ensure ABSL_CXX_STANDARD is set.
Fixes #640

PiperOrigin-RevId: 301160106

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14ca0beee8c109e532134e7e9da7b072da1bf911 by Abseil Team <absl-team@google.com>:

Rollback the change to make Cord iterators a fixed size.  That change increased the iterator size, which can cause a deep recursion call to hit the stack memory limit, in turn causing a signal 11 failure.

PiperOrigin-RevId: 301084915

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619e3cd9e56408bdb8b3b5a1e08dda1e95242264 by Matthew Brown <matthewbr@google.com>:

Internal Change

PiperOrigin-RevId: 300832828

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64f8d62ab4c4c78077dbe85a9595a8eeb6d16608 by Gennadiy Rozental <rogeeff@google.com>:

Fix for empty braces support.

We will call proper aggregate construction in case when {} is used as default value. In other words instead of "new T", we'll call "new T{}".

PiperOrigin-RevId: 300715686

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db3f65594d6db8b104b01262f884dff465b696ef by Abseil Team <absl-team@google.com>:

Emscripten supports thread-local storage nowadays.

PiperOrigin-RevId: 300675185
GitOrigin-RevId: 91ca367a7548270155721bdda74611aeea2a2153
Change-Id: I3344f745f9c3fc78775532b1808442fabd98e34a

ci/macos_xcode_cmake.sh

@@ -36,7 +36,7 @@ for compilation_mode in ${ABSL_CMAKE_BUILD_TYPES}; do
   time cmake ${ABSEIL_ROOT} \
     -GXcode \
     -DCMAKE_BUILD_TYPE=${compilation_mode} \
-    -DCMAKE_CXX_FLAGS=-std=c++14 \
+    -DCMAKE_CXX_STANDARD=11 \
     -DABSL_USE_GOOGLETEST_HEAD=ON \
     -DABSL_RUN_TESTS=ON
   time cmake --build .