tinygo support will need updating for tinygo 0.32

[dkegel-fastly]

Current fwd doesn’t compile with the dev branch of tinygo due to incompatibilities with the reflect package introduced in reflect: use int in StringHeader and SliceHeader on non-AVR platforms by ydnar · Pull Request #4156 · tinygo-org/tinygo .

The symptom is

../../../../../pkg/mod/github.com/philhofer/fwd@v1.1.2/writer_tinygo.go:15:9: cannot use l (variable of type uintptr) as int value in struct literal

A fix might be to use the safer, portable functions suggested in tinygo-org/tinygo#1284 ?

[glycerine]

@philhofer would you mind tagging a version of fwd that has this tinygo fix, so that we can build it/try it within the go module system? I think a "v1.1.3-beta" might do, if you don't want to commit to v1.1.3 yet. ( https://go.dev/doc/modules/version-numbers#pre-release-version ) But of course v1.1.3 would be just fine too :)