Correct abseil dependencies to make it possible to run gn check

//third_party/abseil-cpp is currently excluded from
gn check because of a couple of dependency fails. This patch
tries to fix those.

Most complicated is the dependency to gmock. The code does
include "gmock/gmock.h" which gn will see as a dependency on
//third_party/googletest:gmock.

Bug: 898837
Change-Id: I2c1d33935511e790e1343cb59db11908cf4fab15
Reviewed-on: https://chromium-review.googlesource.com/c/1307497
Commit-Queue: Daniel Bratell <bratell@opera.com>
Reviewed-by: Patrik Höglund <phoglund@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603976}

third_party/abseil-cpp/absl/debugging/BUILD.gn

@@ -92,10 +92,10 @@ source_set("failure_signal_handler") {
   ]
   public_configs = [ "//third_party/abseil-cpp:absl_include_config" ]
   sources = [
-    "failure_signal_handler.cc"
+    "failure_signal_handler.cc",
   ]
   public = [
-    "failure_signal_handler.h"
+    "failure_signal_handler.h",
   ]
   deps = [
     ":examine_stack",
@@ -126,6 +126,7 @@ source_set("debugging_internal") {
   ]
   deps = [
     "../base",
+    "../base:core_headers",
     "../base:dynamic_annotations",
   ]
 }

third_party/abseil-cpp/absl/time/BUILD.gn

@@ -62,8 +62,9 @@ source_set("test_util") {
     ":time",
     "../base",
     "../time/internal/cctz:time_zone",
-    "//testing/gtest",
     "//testing/gmock",
+    "//testing/gtest",
+    "//third_party/googletest/:gmock",
   ]
   visibility = []
   visibility += [ "../time:*" ]

third_party/abseil-cpp/absl/types/BUILD.gn

@@ -104,6 +104,7 @@ source_set("optional") {
   deps = [
     ":bad_optional_access",
     "../base:config",
+    "../base:core_headers",
     "../memory",
     "../meta:type_traits",
     "../utility",