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/BUILD.bazel

@@ -12,19 +12,16 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-#
-
-load(
-    ":compiler_config_setting.bzl",
-    "create_llvm_config",
-)
 
 package(default_visibility = ["//visibility:public"])
 
-licenses(["notice"])  # Apache 2.0
+licenses(["notice"])
 
-create_llvm_config(
-    name = "llvm_compiler",
+config_setting(
+    name = "clang_compiler",
+    flag_values = {
+        "@bazel_tools//tools/cpp:compiler": "clang",
+    },
     visibility = [":__subpackages__"],
 )
 
@@ -58,3 +55,11 @@ config_setting(
     },
     visibility = [":__subpackages__"],
 )
+
+config_setting(
+    name = "wasm",
+    values = {
+        "cpu": "wasm32",
+    },
+    visibility = [":__subpackages__"],
+)