all: make TinyGo code usable with "big Go" CGo

I managed to get CGo sort-of working in VSCode (meaning that it will
typecheck code in the IDE itself) using a few crude hacks, but it
requires a few minor changes to the TinyGo standard library.

I intend to eventually add this support in the TinyGo extension for
VSCode directly, but for now I've manually updated .vscode/settings.json
to get IDE support. In any case, it would be nice to have this for when
I hopefully add this to the TinyGo extension eventually.

src/machine/machine_rp2040_rom.go

@@ -1,4 +1,4 @@
-//go:build rp2040
+//go:build tinygo && rp2040
 
 package machine