It is not directly tested or usable yet, and depends on having
wasi-libc library available at /usr/share/wasi-sysroot.
Still, it compiled, so it's a nice start.
`make wasi` produces `libsql.wasm` module.
Future work includes using this module to run a WebAssembly app
in a runtime that supports WASI, using `libsql.wasm` as the database
implementation.
The patch is based on splitting SQLITE_OMIT_WAL into SQLITE_OMIT_SHARED_MEM,
so that we can still compile WAL mode, just without shared memory,
so still usable with exclusive mode or via libSQL's virtual WAL.
