Expose _apple_platforms on mockingbird_mock

Summary:
We want to be able to able to configure and build mockingbird mocks in the same configuration as they're built in tests.

List these platforms so that it can utilize the same logic as other targets.

Reviewed By: milend

Differential Revision: D63991448

fbshipit-source-id: 75edaedc9206116894105063824eff23600d84c8

apple/mockingbird/mockingbird_mock.bzl

@@ -5,6 +5,7 @@
 # License, Version 2.0 found in the LICENSE-APACHE file in the root directory
 # of this source tree.
 
+load("@prelude//apple:apple_platforms.bzl", "APPLE_PLATFORMS_KEY")
 load("@prelude//user:rule_spec.bzl", "RuleRegistrationSpec")
 load(":mockingbird_types.bzl", "MockingbirdLibraryInfo", "MockingbirdLibraryRecord", "MockingbirdSourcesInfo")
 
@@ -81,6 +82,7 @@ def _attrs():
         "srcs": attrs.set(attrs.source(), sorted = True, default = []),
         "_mockingbird_bin": attrs.exec_dep(providers = [RunInfo], default = "fbsource//fbobjc/VendorLib/Mockingbird:mockingbird-binary"),
         "_mockingbird_support": attrs.dep(providers = [DefaultInfo], default = "fbsource//fbobjc/VendorLib/Mockingbird:MockingbirdSupport"),
+        APPLE_PLATFORMS_KEY: attrs.dict(key = attrs.string(), value = attrs.dep(), sorted = False, default = {}),
     }
     return attribs