avoid some C functions that are not in C99 #102

Job	Run time
ci (tpb, ubuntu-22.04, --pb --threads --enable-libffi, test-some-fast)	29m 15s
ci (a6osx, macos-12)	16m 28s
ci (ta6osx, macos-12)	20m 33s
ci (i3le, ubuntu-22.04)	12m 48s
ci (ti3le, ubuntu-22.04)	16m 9s
ci (a6le, ubuntu-22.04)	8m 59s
ci (ta6le, ubuntu-22.04)	12m 2s
ci (ta6le, ubuntu-22.04, reboot, -m=ta6le --force, re.boot SCHEME="chezscheme", test-some-fast)	8m 54s
ci (i3nt, windows-2022, vs)	11m 43s
ci (ti3nt, windows-2022, vs)	14m 31s
ci (a6nt, windows-2022, vs)	11m 57s
ci (ta6nt, windows-2022, vs)	14m 47s
ci (ta6nt, windows-2022, gcc)	13m 25s
	3h 11m 31s

Provide feedback