[llvm] [bazel] Add support for building lldb (PR #87589)

[Christian Sigg via llvm-commits]

chsigg wrote:

Hi Keith, the [bazel buildkite](https://buildkite.com/llvm-project/upstream-bazel) is not happy with this change.

```
ERROR: Target @llvm-project//lldb:DebugServerCommon is incompatible and cannot be built, but was explicitly requested.
Dependency chain:
    @llvm-project//lldb:DebugServerCommon (4f455a)
    @llvm-project//lldb:DebugServerMacOSX (189b94)   <-- target platform (@local_config_platform//:host) didn't satisfy constraint @platforms//:incompatible
```

Is this something you can fix forward?

https://github.com/llvm/llvm-project/pull/87589