Export of internal Abseil changes.

--
f6c627ce4470a814adc377947b58346eef69a4c9 by Jon Cohen <cohenjon@google.com>:

Don't create install rules when Abseil is used as a subdirectory.

Fix #287

PiperOrigin-RevId: 240559825

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a5d9b06fe736143068997988b654b5f66ec3266a by Matt Calabrese <calabrese@google.com>:

Make absl::nullopt an inline constexpr variable, as specified in the standard (with a workaround for pre-c++17 compilers).

PiperOrigin-RevId: 240552286

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d7bee50cff745fbb8d1cdf56a200d9073d311c80 by Abseil Team <absl-team@google.com>:

Internal Change

PiperOrigin-RevId: 240425622

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828dd49d392d83dbeecd9d3e9cb14551ab265905 by Jon Cohen <cohenjon@google.com>:

Add default link options to absl builds.

Currently all this does is add -ignore:4221 to Abseil msvc builds, but the structure is all in place to add more link options when necessary

Fix #277

Note: This CL changes tact for us in that it puts the default options in the helper function as opposed to the invocations of absl_cc_blah.  The original intent of keeping these out of the helper functions was to make generating the CMakeLists.txt files have a smaller diff, but looking now that is a problem for the future, and small compared to making maintenance and use of our CMake buildsystem easier
PiperOrigin-RevId: 240409463

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4aa120e9dcf76d29e9ca0008d0f6d4d9fa8abe8c by Matt Kulukundis <kfm@google.com>:

Reduce flake rate for non-determistic test to < 1/10,000

PiperOrigin-RevId: 240370938

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bc30e219531827bfbf90915b2067c7fb8160bb6d by Derek Mauro <dmauro@google.com>:

Add Bazel caching on Kokoro for new linux targets.

PiperOrigin-RevId: 240356556

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c4e06d79a50d7bb211312b7845c4bd92c0761747 by Jon Cohen <cohenjon@google.com>:

include AbseilInstallDirs instead of GNUInstallDirs.  It worked before because global_CMakeLists.txt also included AbseilInstallDirs

PiperOrigin-RevId: 240206409

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c254dc6cade8a263f3f97fb1417d92fe5235ff32 by Jon Cohen <cohenjon@google.com>:

Fix logic for when we create the variant_exception_safety_test in CMake.  Currently we are only running in on gcc > 4.9, when we want it run on every compiler except gcc <= 4.8

PiperOrigin-RevId: 240194174

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01518006b351d3670ba1d349cfbcb7dd6f3a8b84 by CJ Johnson <johnsoncj@google.com>:

Removes old implementation warning comment now that InlinedVector has an implementation detail file

PiperOrigin-RevId: 240167265

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eb05355ae8c7397752ab7a65afc9e0a99472ba9d by Jon Cohen <cohenjon@google.com>:

Remove the forward declaration of Span

PiperOrigin-RevId: 240156660

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b7e75aa3933d6e79dd086821cf58d15e72f476f4 by Jon Cohen <cohenjon@google.com>:

Prepare CMake install rule for LTS releases:
  * Remove the warning against installing in system install locations
  * Insert versioning to keep different LTS installs from colliding.  Headers are installed in <prefix>/absl_$version/include, .a files in <prefix>/absl_$version/lib, and config files in <prefix>/absl_$version/lib/cmake

PiperOrigin-RevId: 240153986

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de63488ab6236e041f08260794b0b634a2b8ed16 by CJ Johnson <johnsoncj@google.com>:

Reduce reader confusion by using std::addressof(...) even when the type is known to not overload operator&(...)

PiperOrigin-RevId: 240131902
GitOrigin-RevId: f6c627ce4470a814adc377947b58346eef69a4c9
Change-Id: I95dbbacaaf65aceeeca9e9bee5fd9ea456225f62

absl/synchronization/BUILD.bazel

@@ -17,6 +17,7 @@
 load(
     "//absl:copts/configure_copts.bzl",
     "ABSL_DEFAULT_COPTS",
+    "ABSL_DEFAULT_LINKOPTS",
     "ABSL_TEST_COPTS",
 )
 
@@ -34,6 +35,7 @@ cc_library(
         "internal/graphcycles.h",
     ],
     copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
     visibility = [
         "//absl:__subpackages__",
     ],
@@ -72,7 +74,7 @@ cc_library(
     linkopts = select({
         "//absl:windows": [],
         "//conditions:default": ["-pthread"],
-    }),
+    }) + ABSL_DEFAULT_LINKOPTS,
     deps = [
         ":graphcycles_internal",
         "//absl/base",
@@ -92,9 +94,7 @@ cc_test(
     size = "small",
     srcs = ["barrier_test.cc"],
     copts = ABSL_TEST_COPTS,
-    tags = [
-        "no_test_wasm",
-    ],
+    linkopts = ABSL_DEFAULT_LINKOPTS,
     deps = [
         ":synchronization",
         "//absl/time",
@@ -107,9 +107,7 @@ cc_test(
     size = "small",
     srcs = ["blocking_counter_test.cc"],
     copts = ABSL_TEST_COPTS,
-    tags = [
-        "no_test_wasm",
-    ],
+    linkopts = ABSL_DEFAULT_LINKOPTS,
     deps = [
         ":synchronization",
         "//absl/time",
@@ -122,6 +120,7 @@ cc_test(
     size = "medium",
     srcs = ["internal/graphcycles_test.cc"],
     copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
     deps = [
         ":graphcycles_internal",
         "//absl/base",
@@ -134,6 +133,7 @@ cc_test(
     name = "graphcycles_benchmark",
     srcs = ["internal/graphcycles_benchmark.cc"],
     copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
     tags = [
         "benchmark",
     ],
@@ -148,6 +148,7 @@ cc_library(
     name = "thread_pool",
     testonly = 1,
     hdrs = ["internal/thread_pool.h"],
+    linkopts = ABSL_DEFAULT_LINKOPTS,
     visibility = [
         "//absl:__subpackages__",
     ],
@@ -162,6 +163,7 @@ cc_test(
     size = "large",
     srcs = ["mutex_test.cc"],
     copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
     shard_count = 25,
     deps = [
         ":synchronization",
@@ -179,6 +181,7 @@ cc_library(
     testonly = 1,
     srcs = ["mutex_benchmark.cc"],
     copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
     visibility = [
         "//absl/synchronization:__pkg__",
     ],
@@ -195,6 +198,7 @@ cc_binary(
     name = "mutex_benchmark",
     testonly = 1,
     copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
     visibility = ["//visibility:private"],
     deps = [
         ":mutex_benchmark_common",
@@ -206,6 +210,7 @@ cc_test(
     size = "small",
     srcs = ["notification_test.cc"],
     copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
     deps = [
         ":synchronization",
         "//absl/time",
@@ -218,6 +223,7 @@ cc_library(
     testonly = 1,
     srcs = ["internal/per_thread_sem_test.cc"],
     copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
     deps = [
         ":synchronization",
         "//absl/base",
@@ -232,7 +238,7 @@ cc_test(
     name = "per_thread_sem_test",
     size = "medium",
     copts = ABSL_TEST_COPTS,
-    tags = ["no_test_wasm"],
+    linkopts = ABSL_DEFAULT_LINKOPTS,
     deps = [
         ":per_thread_sem_test_common",
         ":synchronization",
@@ -249,6 +255,7 @@ cc_test(
         "lifetime_test.cc",
     ],
     copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
     tags = ["no_test_ios_x86_64"],
     deps = [
         ":synchronization",