This commit fixes rights check for `fd_pread` and `fd_pwrite` to be
conformant with the WASI spec. In the spec, it is clearly stated that
the right to invoke `__wasi_fd_pread()` requires a combination of
`__WASI_RIGHT_FD_READ` with `__WASI_RIGHT_FD_SEEK`, and similarly for
`__wasi_fd_pwrite()` the combination is `__WASI_RIGHT_FD_WRITE` with
`__WASI_RIGHT_FD_SEEK`. Relevant link to the spec: [__wasi_rights_t].
[__wasi_rights_t]: https://github.com/WebAssembly/WASI/blob/master/phases/snapshot/docs/wasi_unstable_preview1.md#__wasi_rights_t-uint64_t-bitfield
* Reorganize wasi-misc-tests.
Move wasi-misc-tests out of wasi-common, to break a dependency cycle;
previously, wasmtime-* depended on wasi-common, but wasi-common
dev-dependended on wasmtime-*.
Now, wasi-common no longer dev-depends on wasmtime-*; instead, the
tests are in their own crate which depends on wasi-common and on
wasmtime-*.
Also, rename wasi-misc-tests to wasi-tests for simplicity.
This also removes the "wasm_tests" feature; it's replaced by the
"test-programs" feature.
* Update the CI script to use the new feature name.
* Update the CI script to use the new feature name in one more place.
* Change a `write!` to a `writeln!`.
