[compiler-rt] Undo lsan part of #98240 (PR #98409)

[Fangrui Song via llvm-commits]

MaskRay wrote:

This caused 
```
  The binary directory

    /tmp/Debug/projects/compiler-rt/lib/lsan

  is already used to build a source directory.  It cannot be used to build
  source directory
```

even in a clean build `LLVM_ENABLE_PROJECTS='clang;lld;compiler-rt'`. I haven't figured out why

The `COMPILER_RT_HAS_*SAN` cleanup probably caused the whole `lib/lsan/CMakeFiles.txt` to be processed.
I wonder whether it makes sense for `COMPILER_RT_HAS_LSAN`  to skip including `lib/lsan`.

https://github.com/llvm/llvm-project/pull/98409