Properly handle default_package_metadata attribute. (#1217)

* Update buildozer to account for the renaming the global attribute `applicable_licenses` to `package_metadata`.
The previous code assumed that `applicable_licenses` existed, and used
it to set the type for `default_applicable_licenses`.  Now we simply
assume that `default_applicable_licenses` and `default_package_metadata`
are label lists.

* Might as well do the attribute too

generatetables/generate_tables.go

diff --git a/generatetables/generate_tables.go b/generatetables/generate_tables.go
index 0b514e2..c1650f7 100644
--- a/generatetables/generate_tables.go
+++ b/generatetables/generate_tables.go
@@ -74,12 +74,19 @@
 	types["default_copts"] = types["copts"]
 	types["default_deprecation"] = types["deprecation"]
 	types["default_testonly"] = types["testonly"]
-	types["default_applicable_licenses"] = types["applicable_licenses"]
+	types["default_applicable_licenses"] = buildpb.Attribute_LABEL_LIST
+	types["default_package_metadata"] = buildpb.Attribute_LABEL_LIST
 	types["features"] = buildpb.Attribute_STRING_LIST
 
 	types["extra_srcs"] = types["srcs"]
 	types["pytype_deps"] = types["deps"]
 
+	// Make sure we always have this.
+	_, ok := types["package_metadata"]
+	if ! ok {
+		types["package_metadata"] = buildpb.Attribute_LABEL_LIST
+	}
+
 	return types
 }
 

lang/tables.gen.go

diff --git a/lang/tables.gen.go b/lang/tables.gen.go
index 9bee34a..0989f68 100755
--- a/lang/tables.gen.go
+++ b/lang/tables.gen.go
@@ -187,6 +187,7 @@
 	"default_hdrs_check":	buildpb.Attribute_STRING,
 	"default_ios_sdk_version":	buildpb.Attribute_STRING,
 	"default_macos_sdk_version":	buildpb.Attribute_STRING,
+	"default_package_metadata":	buildpb.Attribute_LABEL_LIST,
 	"default_properties":	buildpb.Attribute_LABEL,
 	"default_testonly":	buildpb.Attribute_BOOLEAN,
 	"default_tvos_sdk_version":	buildpb.Attribute_STRING,
@@ -325,6 +326,7 @@
 	"output_to_bindir":	buildpb.Attribute_BOOLEAN,
 	"outs":	buildpb.Attribute_STRING_LIST,
 	"package_configuration":	buildpb.Attribute_LABEL_LIST,
+	"package_metadata":	buildpb.Attribute_LABEL_LIST,
 	"packages":	buildpb.Attribute_LABEL_LIST,
 	"parents":	buildpb.Attribute_LABEL_LIST,
 	"path":	buildpb.Attribute_STRING,