Completely disable signal handler on 32-bit (WebAssembly#1488)

The previous change prevented `WASM_RT_MEMCHECK_SIGNAL_HANDLER_POSIX`
from being defined, but `WASM_RT_MEMCHECK_SIGNAL_HANDLER` was still
defined, which would prevent the memory bounds check.

Use #warning instead of #warn (WebAssembly#1487)

Add install prefix for build releases [skip ci]

Fix typo in build_release.yml

[wasm-c-api] Implement missing functions (WebAssembly#1461)

For now, the wasm-c-api interface in wabt doesn't have its own tests,
and relies on the wasm-c-api repo's examples for testing. This means
that some functions that are not used in any examples were accidentally
omitted.

TODO: wabt (or wasm-c-api) should have explicit tests of the API
surface.

Add build flag to disable build of libwasm (WebAssembly#1435)

This allows the wabt tools to be build with no git submodules

Update emscripten build after SIMD change

Update emscripten build after SIMD change

Initial WASM C API implementation. (WebAssembly#1250)

All tests except `threads` pass.

[wasm2c] Fix realloc check in wasm_rt_grow_memory (WebAssembly#1171)

See issue WebAssembly#1159.