[lldb] Use shutil.which instead of distutils find_executable

[DavidSpickett]

Summary

distutils is deprecated and shutil.which is the suggested
replacement for this function.

https://peps.python.org/pep-0632/#migration-advice
https://docs.python.org/3/library/shutil.html#shutil.which

It was added in Python3.3 but given that we're already using
shutil.which elsewhere I think this is ok/no worse than before.

We do have our own find_executable in lldb/test/Shell/helper/build.py
but I'd rather leave that as is for now. Also we have our own versions
of which() but again, a change for another time.

This work is part of #54337.

[DavidSpickett]

https://reviews.llvm.org/D124429 unblocked doing this.

The github issue is https://github.com/llvm/llvm-project/issues/54337.

Once I know this is ok with the bots I'll see what I can do about our various which re-implementations (I'm sure they have quirks that are easy to miss).

[JDevlieghere]

Thanks!

lldb/packages/Python/lldbsuite/test/lldbtest.py

 import os.path
 import re
 import shutil
 import signal
 from subprocess import *
 import sys
 import time
 import traceback
-import distutils.spawn
 
 # Third-party modules
 import unittest2
 from six import add_metaclass
 from six import StringIO as SixStringIO
 import six
 
 # LLDB modules
def findBuiltClang(self):
             os.path.dirname(__file__), "..", "..", "..", "..")
         for p in paths_to_try:
             path = os.path.join(lldb_root_path, p)
             if os.path.exists(path):
                 return path
 
         # Tries to find clang at the same folder as the lldb
         lldb_dir = os.path.dirname(lldbtest_config.lldbExec)
-        path = distutils.spawn.find_executable("clang", lldb_dir)
+        path = shutil.which("clang", path=lldb_dir)
         if path is not None:
             return path
 
         return os.environ["CC"]
 
 
     def yaml2obj(self, yaml_path, obj_path, max_size=None):
         """

lldb/test/Shell/lit.cfg.py

 # -*- Python -*-
 
 import os
 import platform
 import re
 import shutil
 import site
 import subprocess
 import sys
 
 import lit.formats
 from lit.llvm import llvm_config
 from lit.llvm.subst import FindTool
 from lit.llvm.subst import ToolSubst
-from distutils.spawn import find_executable
 
 site.addsitedir(os.path.dirname(__file__))
 from helper import toolchain
 
 # name: The name of this test suite.
 config.name = 'lldb-shell'
 
 # testFormat: The test format to use to interpret tests.
if config.lldb_enable_python:
     config.available_features.add('python')
 
 if config.lldb_enable_lua:
     config.available_features.add('lua')
 
 if config.lldb_enable_lzma:
     config.available_features.add('lzma')
 
-if find_executable('xz') != None:
+if shutil.which('xz') != None:
     config.available_features.add('xz')
 
 if config.lldb_system_debugserver:
     config.available_features.add('system-debugserver')
 
 # NetBSD permits setting dbregs either if one is root
 # or if user_set_dbregs is enabled
 can_set_dbregs = True