libbinder_ndk: AIBinder_{setRequesting,getCalling}Sid

This adds the following two methods for APEX:
- AIBinder_setRequestingSid
- AIBinder_getCallingSid

This is not made as an SDK API because security contexts are a platform
detail, and the platform header is shared for APEX and platform use
(different from parcel for now).

Fixes: 159135973
Test: libbinder_ndk_unit_test
Change-Id: Iec64577ebbb7a8cc6550d1d211fe5f562337cf0b
diff --git a/libs/binder/ndk/tests/IBinderNdkUnitTest.aidl b/libs/binder/ndk/tests/IBinderNdkUnitTest.aidl
index 6e8e463..4bba9e4 100644
--- a/libs/binder/ndk/tests/IBinderNdkUnitTest.aidl
+++ b/libs/binder/ndk/tests/IBinderNdkUnitTest.aidl
@@ -24,4 +24,6 @@
 interface IBinderNdkUnitTest {
     void takeInterface(IEmpty test);
     void forceFlushCommands();
+
+    boolean getsRequestedSid();
 }