Fix driver warning about -shared-libasan on Android.

Asan runtime library is always shared on Android, and -shared-libasan is no-op.
Suppress the unused argument warning.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@210252 91177308-0d34-0410-b5e6-96231b3b80d8
Fix driver warning about -pthread on Android.

-pthread is no-op on Android. Suppress the unused argument warning.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@210253 91177308-0d34-0410-b5e6-96231b3b80d8