gh-117657: Fix itertools.count thread safety #112957

Job	Run time
Check for source changes	9s
Check if generated files are up to date	1s
Docs	0s
Address sanitizer	1s
Ubuntu SSL tests with OpenSSL (1.1.1w)	1s
Ubuntu SSL tests with OpenSSL (3.0.13)	1s
Hypothesis tests on Ubuntu	1s
Ubuntu SSL tests with OpenSSL (3.1.5)	1s
CIFuzz (address)	1s
Ubuntu SSL tests with OpenSSL (3.2.1)	1s
CIFuzz (undefined)	1s
CIFuzz (memory)	1s
Windows / build and test (x64)	1s
Windows / build and test (x86)	1s
Windows / build (arm64)	1s
macOS / build and test (macos-14)	1s
macOS / build and test (macos-13)	1s
macOS (free-threading) / build and test (macos-14)	1s
Ubuntu / build and test	1s
Ubuntu (free-threading) / build and test	1s
Thread sanitizer / Thread sanitizer	1s
Thread sanitizer (free-threading) / Thread sanitizer	1s
Windows (free-threading) / build and test (x64)	1s
Windows (free-threading) / build (arm64)	1s
Windows (free-threading) / build and test (x86)	1s
WASI / build and test	1s
All required checks pass	4s
	37s

Provide feedback