hiddenapi: Enable assign-all CHECK

Master-art builds now pass --no-force-assign-all to `hiddenapi`. This
enables us to turn a warning that on non-master-art builds all methods
and fields have flags assigned to them. This also fixes logspam on
buildbots.

Test: art/tools/buildbot-build.sh
Bug: 123143676
Change-Id: Id0b57dbe9b0bb809bf22de1fd3b922a0886833ec
diff --git a/tools/hiddenapi/hiddenapi.cc b/tools/hiddenapi/hiddenapi.cc
index 97fbcbf..f426d02 100644
--- a/tools/hiddenapi/hiddenapi.cc
+++ b/tools/hiddenapi/hiddenapi.cc
@@ -974,11 +974,8 @@
           auto fn_shared = [&](const DexMember& boot_member) {
             auto it = api_list.find(boot_member.GetApiEntry());
             bool api_list_found = (it != api_list.end());
-            // TODO: Fix ART buildbots and turn this into a CHECK.
-            if (force_assign_all_ && !api_list_found) {
-              LOG(WARNING) << "Could not find hiddenapi flags for dex entry: "
-                           << boot_member.GetApiEntry();
-            }
+            CHECK(!force_assign_all_ || api_list_found)
+                << "Could not find hiddenapi flags for dex entry: " << boot_member.GetApiEntry();
             builder.WriteFlags(api_list_found ? it->second : ApiList::Whitelist());
           };
           auto fn_field = [&](const ClassAccessor::Field& boot_field) {