Use single module for clang runtime libraries

The clang prebuilts now provide a single module with per-architecture
variants instead of a module per architecture.

Bug: 220019988
Test: m checkbuild
(cherry picked from commit 386ee59a)
Merged-In: I39e2cf8ae14edf8510276dab38011afaef85822c
Change-Id: I3e579002d6509e9e3ef214e007b62260cbeb438c