Get rid of repeated building load.o #6439

Job	Run time
Windows 2025/Visual C++ 2022 (check)	25m 20s
Windows 2025/Visual C++ 2022 (test-bundled-gems)	28m 34s
Windows 11-arm/Visual C++ (btest test-basic test-tool)	16m 59s
Windows 2022/Visual C++ 2022 (check)	24m 45s
Windows result	3s
	1h 35m 41s

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