Add `read_exact_at` and `write_all_at` to WASI's `FileExt`#74076

Merged

bors merged 2 commits intorust-lang:masterfrom

sunfishcode:wasi-fileext-newmethods

Jul 11, 2020

Commits on Jul 7, 2020

Add `read_exact_at` and `write_all_at` to WASI's `FileExt`
sunfishcode
committed
Make WASI's FileExt's read_at/write_at consistent with other targets.
sunfishcode
committed