Remove special-handling of the restricted tag.

Nobody is using it any more, and it'd be too easy to
make a build system change that wouldn't properly handle it.

Change-Id: Ia61232ff944c34c46932c1885b2b0ec1b479566b
diff --git a/core/definitions.mk b/core/definitions.mk
index a355c71..46bc3d1 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -572,6 +572,7 @@
 # $(1): list of tags to accept
 # $(2): list of tags to reject
 #TODO(dbort): do $(if $(strip $(1)),$(1),$(ALL_MODULE_TAGS))
+#TODO(jbq): as of 20100106 nobody uses the second parameter
 define get-tagged-modules
 $(filter-out \
 	$(call modules-for-tag-list,$(2)), \