* Add command line help for "-mexec-model"
* Define WasmExecModel enum in std.builtin.
* Drop the support for the old crt1.o in favor of crt1-command.o
Signed-off-by: Takeshi Yoneda <takeshi@tetrate.io>
* then, in `link/Wasm.zig` map `CRTFile` to full emulated libs name
* move logic for removing any mention of WASI snapshot
`wasi_snapshot_preview1` from `Compilation.zig` into `link/Wasm.zig`
Move parsing of system libs into `main.zig` next to where we decide
if we should link libC, and, if targeting WASI, if the specified
libname equals one of the emulated components, save it on the side
and remove it from the system libs. Then, build *only* those parts
of WASI libc that were preserved in the previous step.
This also fixes building of different crt1 bits needed to support
reactors and commands.
This replicates the expected behavior when using `clang` with
upstream `wasi-libc` sysroot: linking emulated subcomponents
such as process clocks or signals requires an explicit link flag
in the compiler invocation, for example:
```
zig cc -target wasm32-wasi -lwasi-emulated-process-clocks main.c -o main.wasm
```
This commit includes emulated libc sublibs that were not included
in the compilation and caching of WASI libc that ships with Zig.
The libs include (emulated): process clocks, getpid, mman, and signal.
With this change, it is now possible to successfully cross-compile
`wasm3` engine to WASI with `zig cc`.
For the future though, it might be worth considering splitting WASI
libc into libc-proper and modularised emulated libs as it is done
in upstream, and then have them included only if the user specifically
requests emulation/parts of it.
This matches the behaviour of other languages and leaves us
the ability to create actual static Wasm archives with
```
zig build-lib -static some.zig
```
which can then be combined with other Wasm object files and linked
into either a Wasm lib or executable using `wasm-ld`.
Update langref to reflect the fact we now ship WASI libc.
Rename include dir to match the convention:
from `wasm32-wasi` to `wasm-wasi-musl`
Add building stubs which will be used to build and cache WASI
libc sysroot.
