[lldb] Make compiler-rt an optional LLDB test dependency

Make compiler-rt an LLDB test dependency if the corresponding target
exists. Similarly we already have `asan` and `tsan` as optional test
dependencies, but we need the `compiler-rt` target when enabling
compiler-rt trough LLVM_ENABLE_RUNTIMES.

GitOrigin-RevId: 52465dc17877d742aad737622e0da04aea2d72cb
1 file changed