chore: import upstream snapshot with attribution

third_party/absl/BUILD

@@ -0,0 +1 @@
+# copybara:uncomment package(default_applicable_licenses = ["//tensorflow:license"])

third_party/absl/build_dll.patch

@@ -0,0 +1,43 @@
+diff --git a/absl/BUILD.bazel b/absl/BUILD.bazel
+--- a/absl/BUILD.bazel
++++ b/absl/BUILD.bazel
+@@ -15,11 +15,26 @@
+ #
+ 
+ load("@bazel_skylib//lib:selects.bzl", "selects")
++load("@bazel_skylib//rules:common_settings.bzl", "bool_flag")
+ 
+ package(default_visibility = ["//visibility:public"])
+ 
+ licenses(["notice"])
+ 
++bool_flag(
++    name = "use_dlls",
++    build_setting_default = False,
++    visibility = ["//visibility:public"],
++)
++
++config_setting(
++    name = "config_use_dlls",
++    flag_values = {
++        ":use_dlls": "True",
++    },
++    visibility = [":__subpackages__"],
++)
++
+ config_setting(
+     name = "clang_compiler",
+     flag_values = {
+diff --git a/absl/copts/configure_copts.bzl b/absl/copts/configure_copts.bzl
+--- a/absl/copts/configure_copts.bzl
++++ b/absl/copts/configure_copts.bzl
+@@ -23,6 +23,9 @@ ABSL_DEFAULT_COPTS = select({
+     "@rules_cc//cc/compiler:clang": ABSL_LLVM_FLAGS,
+     "@rules_cc//cc/compiler:gcc": ABSL_GCC_FLAGS,
+     "//conditions:default": [],
++}) + select({
++    "//absl:config_use_dlls": ["/DABSL_BUILD_DLL"],
++    "//conditions:default": [],
+ })
+ 
+ ABSL_TEST_COPTS = select({

third_party/absl/endian.patch

@@ -0,0 +1,14 @@
+diff --git a/absl/base/BUILD.bazel b/absl/base/BUILD.bazel
+--- a/absl/base/BUILD.bazel
++++ b/absl/base/BUILD.bazel
+@@ -542,10 +542,6 @@ cc_library(
+     ],
+     copts = ABSL_DEFAULT_COPTS,
+     linkopts = ABSL_DEFAULT_LINKOPTS,
+-    visibility = [
+-        "//absl:__subpackages__",
+-        "//absl:friends",
+-    ],
+     deps = [
+         ":base",
+         ":config",