This adds support for `-gc=boehm` on `-target=wasip1` and `-target=wasm`
(in a browser or NodeJS). Notably it does *not* add Boehm GC support for
`-target=wasip2`, since that target doesn't have a real libc.
This adds support for the 'go install' case, where we link against the
system LLVM (Homebrew, Linux distro version, etc). This does not have an
effect on `make`, which still uses LLVM 19 for now.
The main reason for doing this is because newer distros like Fedora 42
and Homebrew have switched to LLVM 20, so switching to this newer
version helps those people. (I'm one of those people, I'm on Fedora 42).
There are two small changes for WebAssembly included:
* nontrapping-fptoint was enabled in the wasmbuiltin library used for
wasm-unknown. This matches wasm-unknown which already had this
enabled, so it doesn't add any new instructions.
* bulk-memory was enabled in wasi-libc. This was previously enabled in
all the other WebAssembly targets (wasm, wasip1, wasip2) so this
does't add any new instructions. I think it was also enabled in the
wasi-libc build before
https://github.com/tinygo-org/tinygo/pull/4820 but I don't know for
sure.
Instead of relying on a build when TinyGo is being built, do it like all
other libraries when it is needed.
This brings a few benefits:
* No more running `make wasi-libc` on the command line as a special
case for WebAssembly. The generic `git submodule update --init` step
is now enough for wasi-libc.
* It becomes much easier to customize the build per system. For
example: include/exclude malloc as needed, disable/enable bulk
memory operations per target, etc.
Ayke van Laethem