build: remove dependency on distutils.spawn

Debian based packages of Python 3 do not include `distutils.spawn` and
require an additional apt package to be installed (`python3-distutils`).
Replace use of `distutils.spawn` with `shutil.which`, available in all
versions of Python currently allowed by our configure scripts.

For the `configure` script only, fall back to `distutils.spawn` to allow
friendlier error messages when run on older unsupported versions of
Python (e.g. 2.7).

`configure.py` also uses `distutils.version` -- this appears to be
available in Debian packaged Python 3 without installing
`python3-distutils` so has been left as-is.

PR-URL: #38600
Refs: #30189
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Christian Clauss <cclauss@me.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

BUILDING.md

@@ -250,8 +250,6 @@ Installation via Linux package manager can be achieved with:
 
 FreeBSD and OpenBSD users may also need to install `libexecinfo`.
 
-Python 3 users may also need to install `python3-distutils`.
-
 #### macOS prerequisites
 
 * Xcode Command Line Tools >= 10 for macOS
@@ -277,11 +275,6 @@ $ ./configure
 $ make -j4
 ```
 
-If you run into a `No module named 'distutils.spawn'` error when executing
-`./configure`, please try `python3 -m pip install --upgrade setuptools` or
-`sudo apt install python3-distutils -y`.
-For more information, see <https://github.com/nodejs/node/issues/30189>.
-
 The `-j4` option will cause `make` to run 4 simultaneous compilation jobs which
 may reduce build time. For more information, see the
 [GNU Make Documentation](https://www.gnu.org/software/make/manual/html_node/Parallel.html).

configure

@@ -18,7 +18,10 @@ exec python "$0" "$@"
 del _
 
 import sys
-from distutils.spawn import find_executable
+try:
+  from shutil import which
+except ImportError:
+  from distutils.spawn import find_executable as which
 
 print('Node.js configure: Found Python {0}.{1}.{2}...'.format(*sys.version_info))
 acceptable_pythons = ((3, 9), (3, 8), (3, 7), (3, 6), (3, 5), (2, 7))
@@ -28,7 +31,7 @@ else:
   python_cmds = ['python{0}.{1}'.format(*vers) for vers in acceptable_pythons]
   sys.stderr.write('Please use {0}.\n'.format(' or '.join(python_cmds)))
   for python_cmd in python_cmds:
-      python_cmd_path = find_executable(python_cmd)
+      python_cmd_path = which(python_cmd)
       if python_cmd_path and 'pyenv/shims' not in python_cmd_path:
         sys.stderr.write('\t{0} {1}\n'.format(python_cmd_path,
                                               ' '.join(sys.argv[:1])))

configure.py

@@ -14,7 +14,7 @@
 import bz2
 import io
 
-from distutils.spawn import find_executable as which
+from shutil import which
 from distutils.version import StrictVersion
 
 # If not run from node/, cd to node/.