merge(3p/absl): subtree merge of Abseil up to e19260f

... notably, this includes Abseil's own StatusOr type, which
conflicted with our implementation (that was taken from TensorFlow).

Change-Id: Ie7d6764b64055caaeb8dc7b6b9d066291e6b538f

third_party/abseil_cpp/absl/synchronization/BUILD.bazel

@@ -24,7 +24,7 @@ load(
 
 package(default_visibility = ["//visibility:public"])
 
-licenses(["notice"])  # Apache 2.0
+licenses(["notice"])
 
 # Internal data structure for efficiently detecting mutex dependency cycles
 cc_library(
@@ -73,15 +73,14 @@ cc_library(
         "internal/create_thread_identity.cc",
         "internal/per_thread_sem.cc",
         "internal/waiter.cc",
+        "mutex.cc",
         "notification.cc",
-    ] + select({
-        "//conditions:default": ["mutex.cc"],
-    }),
+    ],
     hdrs = [
         "barrier.h",
         "blocking_counter.h",
         "internal/create_thread_identity.h",
-        "internal/mutex_nonprod.inc",
+        "internal/futex.h",
         "internal/per_thread_sem.h",
         "internal/waiter.h",
         "mutex.h",
@@ -90,6 +89,7 @@ cc_library(
     copts = ABSL_DEFAULT_COPTS,
     linkopts = select({
         "//absl:windows": [],
+        "//absl:wasm": [],
         "//conditions:default": ["-pthread"],
     }) + ABSL_DEFAULT_LINKOPTS,
     deps = [
@@ -189,6 +189,7 @@ cc_test(
         ":synchronization",
         ":thread_pool",
         "//absl/base",
+        "//absl/base:config",
         "//absl/base:core_headers",
         "//absl/base:raw_logging_internal",
         "//absl/memory",
@@ -210,6 +211,7 @@ cc_library(
         ":synchronization",
         ":thread_pool",
         "//absl/base",
+        "//absl/base:config",
         "@com_github_google_benchmark//:benchmark_main",
     ],
     alwayslink = 1,
@@ -248,6 +250,7 @@ cc_library(
     deps = [
         ":synchronization",
         "//absl/base",
+        "//absl/base:config",
         "//absl/strings",
         "//absl/time",
         "@com_google_googletest//:gtest",