build: define python when generating out/Makefile

[avivkeller]

Ref: #48462

Equal to

node/configure.py

Lines 2363 to 2372 in d74c498

	# Remove the trailing .exe from the executable name, otherwise the python.exe
	# would be rewrote as python_host.exe due to hack in GYP for supporting cross
	# compilation on Windows.
	# See https://github.com/nodejs/node/pull/32867 for related change.
	python = sys.executable
	if flavor == 'win' and python.lower().endswith('.exe'):
	python = python[:-4]
	# Always set 'python' variable, otherwise environments that only have python3
	# will fail to run python scripts.
	gyp_args += ['-Dpython=' + python]

When out/Makefile is generated during ./configure, -Dpython= is passed to GYP, however, when it's generated from the Makefile, it is not passed. This can lead to an undefined variable python on some systems.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.73%. Comparing base (d12ee6e) to head (8b8afa1).
Report is 23 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #57970      +/-   ##
==========================================
- Coverage   90.26%   89.73%   -0.53%     
==========================================
  Files         630      630              
  Lines      186170   186170              
  Branches    36478    36164     -314     
==========================================
- Hits       168042   167066     -976     
- Misses      10982    11937     +955     
- Partials     7146     7167      +21     

see 101 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/66429/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/66430/