Soong can rename these automatically for internal use, so don't require
users to set these.
Bug: 33241851
Test: Android-aosp_arm.mk is the same before/after
Test: build.ninja is the same before/after
Test: build-aosp_arm.ninja is the same before/after
Merged-In: Ia92356a0ec079f908fd49812231228046783e50d
Change-Id: Ia92356a0ec079f908fd49812231228046783e50d