TSAN: Generate TSAN clang rt libs for riscv64

[prashanthswami]

To be at parity with other architectures in the Android NDK, we would like to have the libclang_rt.tsan-riscv64-android.so library included as part of the imported sysroot from Android (Clang Prebuilts). This is distinct from it actually working, which is tracked here: android/ndk#1041 .

[pirama-arumuga-nainar]

https://reviews.llvm.org/D145214 enables tsan runtime for riscv64.

[enh-google]

seems like no-one's reviewed that change yet. @appujee --- is that something we can help with?

[appujee]

let me reach out to the author if he is still working on it.

[appujee]

nobody responded to my query on discord. I can commandeer the patch and put for review.

[appujee]

Update: The author is waiting on review as the patch is feature complete. I've pinged the reviewers

[appujee]

Update: I pinged reviewers to take another look.
Except for minor nits, the reviewers are okay with the patch but would like dvyukov to take a look. I've pinged him.

[appujee]

Merged.
llvm/llvm-project#68735
I tested it on licheepi board as well.