gh-102013: Move PyUnstable_GC_VisitObjects() to Include/cpython/objim… #6

Job	Run time
i686-pc-windows-msvc/msvc (Debug)	15m 18s
i686-pc-windows-msvc/msvc (Release)	19m 45s
x86_64-pc-windows-msvc/msvc (Debug)	15m 25s
x86_64-pc-windows-msvc/msvc (Release)	20m 2s
x86_64-apple-darwin/clang (Debug)	13m 27s
x86_64-apple-darwin/clang (Release)	15m 58s
aarch64-apple-darwin/clang (Debug)	8m 42s
aarch64-apple-darwin/clang (Release)	12m 9s
x86_64-unknown-linux-gnu/gcc (Debug)	6m 56s
x86_64-unknown-linux-gnu/gcc (Release)	16m 22s
x86_64-unknown-linux-gnu/clang (Debug)	7m 13s
x86_64-unknown-linux-gnu/clang (Release)	12m 47s
aarch64-unknown-linux-gnu/gcc (Debug)	55m 30s
aarch64-unknown-linux-gnu/gcc (Release)	45m 13s
aarch64-unknown-linux-gnu/clang (Debug)	50m 53s
aarch64-unknown-linux-gnu/clang (Release)	30m 0s
	5h 45m 40s

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