Support portable boot files on more platforms #65

Job	Run time
ci (tpb, ubuntu-22.04, --pb --threads --enable-libffi, test-some-fast)	38m 13s
ci (a6osx, macos-12)	27m 25s
ci (ta6osx, macos-12)	22m 42s
ci (i3le, ubuntu-22.04)	19m 21s
ci (ti3le, ubuntu-22.04)	15m 44s
ci (a6le, ubuntu-22.04)	13m 45s
ci (ta6le, ubuntu-22.04)	12m 31s
ci (ta6le, ubuntu-22.04, reboot, -m=ta6le --force, re.boot SCHEME="chezscheme", test-some-fast)	9m 1s
ci (i3nt, windows-2022, vs)	11m 33s
ci (ti3nt, windows-2022, vs)	22m 48s
ci (a6nt, windows-2022, vs)	12m 35s
ci (ta6nt, windows-2022, vs)	15m 47s
ci (ta6nt, windows-2022, gcc)	20m 39s
	4h 2m 4s

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