gh-109981: Fix support.fd_count() on macOS 14 #95925

Job	Run time
Check for source changes	9s
Check if generated files are up to date	5m 54s
Address sanitizer	6m 52s
Ubuntu SSL tests with OpenSSL (1.1.1w)	1m 59s
Hypothesis tests on Ubuntu	4m 19s
CIFuzz	0s
Ubuntu SSL tests with OpenSSL (3.0.11)	2m 11s
Ubuntu SSL tests with OpenSSL (3.1.3)	2m 20s
macOS / build and test	11m 37s
macOS (free-threaded) / build and test	17m 28s
Ubuntu / build and test	6m 5s
Ubuntu (free-threaded) / build and test	6m 27s
Windows / build and test (x64)	14m 27s
Windows / build (arm64)	2m 50s
Windows / build and test (x86)	14m 55s
Windows (free-threaded) / build and test (x64)	14m 11s
Windows (free-threaded) / build (arm64)	3m 30s
Windows (free-threaded) / build and test (x86)	15m 43s
Docs / Docs	2m 9s
Docs / Docs (Oldest Sphinx)	1m 43s
Docs / Doctest	7m 25s
All required checks pass	2s
	2h 22m 16s

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