[compiler-rt] [rtsan] Restrict arches and disable android (PR #98268)

[Chris Apple via llvm-commits]

cjappl wrote:

Alright, I think there is still something fishy going on. There are some errors coming to my inbox that look like this:

```
Step 12 (ninja check 2) failure: stage 2 checked (failure)
******************** TEST 'RealtimeSanitizer-Unit :: ./Rtsan-aarch64-NoInstTest/failed_to_discover_tests_from_gtest' FAILED ********************
Step 5 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'RealtimeSanitizer-Unit :: ./Rtsan-s390x-NoInstTest/failed_to_discover_tests_from_gtest' FAILED ********************
```

Anyone have any bright ideas as to why on some systems these tests would be non-discoverable? Digging into it now, but open to any theories 

https://github.com/llvm/llvm-project/pull/98268