Bootstrap panics if lldb fails to start

[ChrisDenton]

Running ./x test tests/ui --stage 1 on Windows I get:

thread 'main' panicked at src\core\build_steps\test.rs:1820:40:
"lldb" "-P" failed Output { status: ExitStatus(ExitStatus(3221225781)), stdout: "", stderr: "" }

This seems especially unfortunate because (as far as I know) ui tests don't require lldb. It works fine if there's no lldb in PATH at least.

This is ultimately an LLVM issue caused by not installing/shipping its own dependencies (in this case Python310). However, bootstrap shouldn't crash here. It should be treated similarly to lldb not existing unless it is actually necessary,

[jieyouxu]

The temporary workaround is ensuring that

you also need python310.dll in PATH otherwise bootstrap errors