add `__wasilibc_reset_preopens` (#489) #1162

Job	Run time
wasi-headers test	0s
Rustfmt	13s
Build libc (ubuntu-latest, 10.0.0)	1m 43s
Build libc (macos-latest, 10.0.0)	2m 52s
Build libc (windows-latest, 10.0.0)	3m 5s
Build libc (ubuntu-latest, 16.0.0, x86_64-linux-gnu-ubuntu-18.04)	3m 5s
Build libc (macos-latest, 15.0.7, x86_64-apple-darwin21.0)	5m 6s
Build libc (windows-latest, 16.0.0)	5m 26s
	21m 30s

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