common: Make it compile

* Provide our own hal_attribute macro but without neverallows
* Workaround silly issue when compiling system_ext public sepolicy
  without any rules

Change-Id: Id7eb04bd049b13380e69a0367fb588f226a93980
diff --git a/sepolicy/public/file.te b/sepolicy/public/file.te
new file mode 100644
index 0000000..871b09e
--- /dev/null
+++ b/sepolicy/public/file.te
@@ -0,0 +1 @@
+type dummy_type_meant_to_prevent_selinux_compilation_from_failing_when_system_ext_public_dir_has_nothing_but_attributes;