refine kernel compilation for threading modes #83

Job	Run time
ci (tpb, ubuntu-22.04, --pb --threads --enable-libffi, test-some-fast)	30m 38s
ci (tpb, ubuntu-22.04, --pb --threads --enable-libffi, test-some-fast)	30m 38s
ci (a6osx, macos-12)	15m 48s
ci (a6osx, macos-12)	15m 48s
ci (ta6osx, macos-12)	20m 7s
ci (ta6osx, macos-12)	20m 7s
ci (i3le, ubuntu-22.04)	12m 52s
ci (i3le, ubuntu-22.04)	12m 52s
ci (ti3le, ubuntu-22.04)	16m 14s
ci (ti3le, ubuntu-22.04)	16m 14s
ci (a6le, ubuntu-22.04)	9m 32s
ci (a6le, ubuntu-22.04)	9m 32s
ci (ta6le, ubuntu-22.04)	12m 16s
ci (ta6le, ubuntu-22.04)	12m 16s
ci (ta6le, ubuntu-22.04, reboot, -m=ta6le --force, re.boot SCHEME="chezscheme", test-some-fast)	8m 36s
ci (ta6le, ubuntu-22.04, reboot, -m=ta6le --force, re.boot SCHEME="chezscheme", test-some-fast)	8m 36s
ci (i3nt, windows-2022, vs)	11m 52s
ci (i3nt, windows-2022, vs)	11m 52s
ci (ti3nt, windows-2022, vs)	14m 54s
ci (ti3nt, windows-2022, vs)	14m 54s
ci (a6nt, windows-2022, vs)	12m 58s
ci (a6nt, windows-2022, vs)	12m 58s
ci (ta6nt, windows-2022, vs)	15m 50s
ci (ta6nt, windows-2022, vs)	15m 50s
ci (ta6nt, windows-2022, gcc)	13m 23s
ci (ta6nt, windows-2022, gcc)	13m 18s
	6h 29m 55s

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