libbinder: Hide AppOpsManager/Service from vendor.

Vendor apps can still use these behind stable SDK or NDK APIs as
applicable, but native code on the vendor image can't use these APIs
because they are using /dev/vndbinder and have an incompatible copy of
libbinder. Since no vendor binary is serving this, removing extra pound
defines and making the vendor version of this library slightly smaller.

Bug: 124524556
Test: builds (no vendor code has added dependencies on this yet)
Change-Id: Idf01641d4b340ca6fe33c181969507ec071ef930