This ensures that breakpoint command honors the scripting language
passed with `-s`. Currently the argument ignores the actual language and
only uses it to differentiate between lldb and script commands.
Don't create a new lua state on every operation. Share a single state
across the lifetime of the script interpreter. Add simple locking to
prevent two threads from modifying the state concurrently.
This implements a very elementary Lua script interpreter. It supports
running a single command as well as running interactively. It uses
editline if available. It's still missing a bunch of stuff though. Some
things that I intentionally ingored for now are that I/O isn't properly
hooked up (so every print goes to stdout) and the non-editline support
which is not handling a bunch of corner cases. The latter is a matter of
reusing existing code in the Python interpreter.
Discussion on the mailing list:
http://lists.llvm.org/pipermail/lldb-dev/2019-December/015812.html
Differential revision: https://reviews.llvm.org/D71234
Create a new test for lldb launched without a script interpreter and
move it under a new `ScriptInterpreter` directory. Also move
crashlog.test there for consistency.
