cmd/compile: make -A and -newexport compatible

cmd/compile: make -A and -newexport compatible

Packages compiled with -A may reference the builtin "any" type, so it
needs to be included in the list of predeclared types for binary
import/export.

Also, when -A is used, mark all symbols as SymExport instead of
SymPackage in importsym.  This parallels the logic in autoexport and
is necessary to prevent a "export/package mismatch" errors in
exportsym during dumpexport's verifyExport pass.

Change-Id: Iff5ec5fbfe2219525ec9d1a975307fa8936af9b9
Reviewed-on: https://go-review.googlesource.com/19627
Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>