Please elaborate on installation instructions for unsupported platforms

[bsiegert]

The README says:

Building on other platforms will need to arrange to build Wasmtime and use CGO_* env vars to compile correctly.

Can you please elaborate on which environment variables and how to build wasmtime?

I am trying to package something depending on wasmtime-go in pkgsrc. We support many more platforms than you have precompiled binaries for, so I would like to always build wasmtime from source.

[alexcrichton]

I believe you need to set CGO_LDFLAGS with -L to where the library lives, but I've not done this before myself so I'm not sure. I forget what I meant when I wrote that in the README, though, sorry.