[Driver] Do not add -lpthread & -lrt with -static-libsan on Android

Summary:
I am not sure anyone has tried to compile an application with sanitizers on
Android with `-static-libsan`, and a recent NDK, but it fails with:
```
.../i686-linux-android/bin/ld.gold: error: cannot find -lpthread
.../i686-linux-android/bin/ld.gold: error: cannot find -lrt
```
My understanding is that both are included in Bionic and as such are not needed,
and actually error out.

So remove the addition of those two in `linkSanitizerRuntimeDeps` when dealing
with Android, and update the tests.

I am unfamiliar with the evolution of the NDK and I am not sure if this has
always been the case or if this is somewhat of a recent evolution. I'll let
Android people chime in.

Reviewers: eugenis, pirama, srhines

Reviewed By: eugenis, srhines

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D48570

llvm-svn: 335620