gh-126366: Make native generators thread safe #2089

Job	Run time
Interpreter (Debug)	7m 3s
Free-Threaded (Debug) (19)	11m 6s
i686-pc-windows-msvc/msvc (Debug)	19m 4s
i686-pc-windows-msvc/msvc (Release)	23m 27s
x86_64-pc-windows-msvc/msvc (Debug)	19m 36s
x86_64-pc-windows-msvc/msvc (Release)	21m 55s
aarch64-pc-windows-msvc/msvc (Debug)	5m 31s
aarch64-pc-windows-msvc/msvc (Release)	6m 23s
x86_64-apple-darwin/clang (Debug)	16m 7s
x86_64-apple-darwin/clang (Release)	22m 41s
x86_64-unknown-linux-gnu/gcc (Debug)	8m 21s
x86_64-unknown-linux-gnu/gcc (Release)	18m 33s
x86_64-unknown-linux-gnu/clang (Debug)	8m 13s
x86_64-unknown-linux-gnu/clang (Release)	13m 21s
aarch64-unknown-linux-gnu/gcc (Debug)	1h 16m 49s
aarch64-unknown-linux-gnu/gcc (Release)	37m 9s
aarch64-unknown-linux-gnu/clang (Debug)	1h 8m 46s
aarch64-unknown-linux-gnu/clang (Release)	37m 31s
	7h 1m 36s

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