build: add luacheck support for package/features

.luacheckrc

@@ -12,6 +12,7 @@ include_files = {
 	"**/*.lua",
 	"package/**/luasrc/**/*",
 	"targets/*",
+	"package/features",
 }
 
 exclude_files = {
@@ -104,3 +105,10 @@ files["targets/*"] = {
 		"try_config",
 	},
 }
+
+files["package/features"] = {
+	read_globals = {
+		"_",
+		"feature",
+	},
+}