fix: allow failure of building linux native binary

[eitsupi]

Ref: #4 (comment)

The issue here is that native binaries may be required, but since subsequent Emscripten builds may succeed without them in fact (which is the case for the original Rust dependency package), we can simply allow the build to fail.

[jeroen]

Wouldn't it still be useful to update the stable toolchain (if the parent image is very old)?

[eitsupi]

Sorry, I was mistaken. In fact, the nightly toolchain is set to default in the base image, so upgrating stable is not helpful.
https://github.com/r-wasm/webr/blob/69d6b0b5e77a9df27d4489df4600a46f7ebae56e/Dockerfile#L45

[eitsupi]

Thanks!