go/internal/gccgoimporter: ignore unexported and imported names
go/internal/gccgoimporter: ignore unexported and imported names

Due to inlining, we can now see unexported functions and variables,
and functions and variables imported from different packages.
Ignore them rather than reporting them from this package.

Handle $hash and $equal functions consistently, so that we discard the
inline body if there is one.

Ignore names created for result parameters for inlining purposes.

Change-Id: I9ae34e0c9470ee99efca27e29bf94f86d290753c
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/180758
Reviewed-by: Than McIntosh <4b2922593166fc595a9b1a408f34f5d3817fe9d2@google.com>

golang/gofrontend,golang/gofrontend,golang/gofrontend,golang/gofrontend