cmd/compile/internal/types2: move some functions into different files (cleanup)
- move structuralType/structuralString into type.go
- move functions exported for the compiler into compilersupport.go
- updated/added comments
- removed AsNamed and AsInterface - not needed by compiler
No semantic changes.
Change-Id: Ia454a49edafd627c2a25b0b71db4aa93ddd7f1f2
Reviewed-on: https://go-review.googlesource.com/c/go/+/362995
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Robert Findley <rfindley@google.com>