* Add DWARF debugging information to all artifacts by default
This commit adds DWARF debugging information with the `-g` compiler flag
to all WASI artifacts for wasi-sdk. The LLVM build itself does not have
debugging information, only the sysroot artifacts. This is intended to
assist with debugging. The main downside to this is binary size of
generated artifacts will, by default, be larger. Stripping debug
information from an artifact though involves removing custom sections
which is generally pretty easy to do through wasm tooling.
* Pass extra cflags to wasi-libc
* Fix tests from previous commit
* Update some expected error messages and remove some files with
duplicate error messages that are no longer needed.
* Remove undefined behavior in `stat.c` where padding bytes were being
compared.