Make specialization of LOAD_GLOBAL thread-safe #87

Job	Run time
Interpreter (Debug)	6m 56s
Free-Threaded (Debug)	10m 13s
i686-pc-windows-msvc/msvc (Debug)	18m 18s
i686-pc-windows-msvc/msvc (Release)	21m 15s
x86_64-pc-windows-msvc/msvc (Debug)	18m 10s
x86_64-pc-windows-msvc/msvc (Release)	16m 31s
aarch64-pc-windows-msvc/msvc (Debug)	4m 56s
aarch64-pc-windows-msvc/msvc (Release)	6m 15s
x86_64-apple-darwin/clang (Debug)	13m 21s
x86_64-apple-darwin/clang (Release)	14m 47s
aarch64-apple-darwin/clang (Debug)	8m 27s
aarch64-apple-darwin/clang (Release)	13m 0s
x86_64-unknown-linux-gnu/gcc (Debug)	7m 57s
x86_64-unknown-linux-gnu/gcc (Release)	17m 25s
x86_64-unknown-linux-gnu/clang (Debug)	7m 40s
x86_64-unknown-linux-gnu/clang (Release)	14m 20s
aarch64-unknown-linux-gnu/gcc (Debug)	1h 13m 10s
aarch64-unknown-linux-gnu/gcc (Release)	35m 50s
aarch64-unknown-linux-gnu/clang (Debug)	1h 7m 27s
aarch64-unknown-linux-gnu/clang (Release)	37m 24s
	6h 53m 22s

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