Remove an API that doesn't exist.

Apparently this was removed in Jelly Bean:
https://stackoverflow.com/q/24312632/632035. Keeping the decl in the
NDK just confuses people: https://stackoverflow.com/q/49646596/632035.

Test: make checkbuild
Bug: None
Change-Id: Id6cfc5df8418e1c872697ff64f9b86fe135b9dc8