add `__wasilibc_reset_preopens` #55

Job	Run time
wasi-headers test	0s
Rustfmt	13s
Build libc (ubuntu-latest, 10.0.0)	2m 12s
Build libc (macos-latest, 10.0.0)	2m 33s
Build libc (windows-latest, 10.0.0)	3m 45s
Build libc (ubuntu-latest, 16.0.0, x86_64-linux-gnu-ubuntu-18.04)	3m 52s
Build libc (macos-latest, 15.0.7, x86_64-apple-darwin21.0)	4m 30s
Build libc (windows-latest, 16.0.0)	5m 27s
	22m 32s

Provide feedback