*-freeze-api does nothing when current == latest stable version

This change fixes a bug that freezing an AIDL interface always create a
new version even when the current version is exactly the same as the
latest stable version.

Bug: 188713899
Test: m aidl-freeze-api

Merged-In: I506062ca8ec8ee1ef0744784af2419dfd8b9471e
Change-Id: I506062ca8ec8ee1ef0744784af2419dfd8b9471e
1 file changed