Export of internal Abseil changes

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167cd2647144583746311129b0cc98a89a9897e1 by Andy Soffer <asoffer@google.com>:

Internal Changes

PiperOrigin-RevId: 268000987

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ab44fea7dfdaf763c69609a08ddfac22480ce520 by Derek Mauro <dmauro@google.com>:

Fix flags Cmake tests on Windows

PiperOrigin-RevId: 267859442

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d7ec9f7611370b01bc9a5aed7e18460df2a15429 by Abseil Team <absl-team@google.com>:

Fix undefined behavior in symbolize_elf.inc

PiperOrigin-RevId: 267684904

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e7c5f8e472a91ed99bdf4876942f2bda5751aa6c by Abseil Team <absl-team@google.com>:

Turn off ABSL_HAS_ALARM on Fuchsia.

PiperOrigin-RevId: 267666090

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b7d25d5c71a49e697a8bf6440ed30f2e3f036420 by Chris Kennelly <ckennelly@google.com>:

Mark once initialization function as no inline.

We expect this code to run infrequently.

PiperOrigin-RevId: 267649713

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dc2a5e5f1e39a03fff837d34a319033fde55d9ba by Derek Mauro <dmauro@google.com>:

Fix the MSVC CMake random build

PiperOrigin-RevId: 267624074

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ba2751b67fa17d1b6c53e5ba79f81a5371e4a03a by Abseil Team <absl-team@google.com>:

Move "internal/flag.*" files to the "internal" build target.

PiperOrigin-RevId: 267588996

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05b985a33eec4f8acff1809ad9218a1e22220f34 by Abseil Team <absl-team@google.com>:

Move "internal/flag.*" files to the "internal" build target.

PiperOrigin-RevId: 267580412
GitOrigin-RevId: 167cd2647144583746311129b0cc98a89a9897e1
Change-Id: Ibd334f46a5671c7c1d3fcf5354029e2fbb7ba91f