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/status/CMakeLists.txt

@@ -19,6 +19,7 @@ absl_cc_library(
   HDRS
     "status.h"
   SRCS
+    "internal/status_internal.h"
     "status.cc"
     "status_payload_printer.h"
     "status_payload_printer.cc"
@@ -39,24 +40,6 @@ absl_cc_library(
   PUBLIC
 )
 
-absl_cc_library(
-  NAME
-    statusor
-  HDRS
-    "statusor.h"
-  SRCS
-    "statusor.cc"
-    "statusor_internals.h"
-  COPTS
-    ${ABSL_DEFAULT_COPTS}
-  DEPS
-    absl::status
-    absl::atomic_hook
-    absl::raw_logging_internal
-    absl::strings
-  PUBLIC
-)
-
 absl_cc_test(
   NAME
     status_test
@@ -70,6 +53,27 @@ absl_cc_test(
     gmock_main
 )
 
+absl_cc_library(
+  NAME
+    statusor
+  HDRS
+    "statusor.h"
+  SRCS
+    "statusor.cc"
+    "internal/statusor_internal.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  DEPS
+    absl::status
+    absl::core_headers
+    absl::raw_logging_internal
+    absl::type_traits
+    absl::strings
+    absl::utility
+    absl::variant
+  PUBLIC
+)
+
 absl_cc_test(
   NAME
     statusor_test
@@ -80,6 +84,5 @@ absl_cc_test(
   DEPS
     absl::status
     absl::statusor
-    absl::strings
     gmock_main
 )