[asan] Disable preload tests on Android.

They don't test what they claim to because LD_PRELOAD applies to "not" instead
of the actual test binary. And all Android tests run with LD_PRELOAD anyway.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@222835 91177308-0d34-0410-b5e6-96231b3b80d8