cmd/compile: use Type.OrigSym getter/setters [generated]

cmd/compile: use Type.OrigSym getter/setters [generated]

Automated CL to rewrite existing code to use OrigSym getters and
setters. Afterwards, we also unexported OrigSym, and then rename the
getter to OrigSym.

[git-generate]
cd src/cmd/compile/internal

: Workaround rf issue with types2 tests.
rm types2/*_test.go

rf '
ex ./noder ./typecheck {
import "cmd/compile/internal/types"
var s *types.Sym
var t *types.Type

t.OrigSym = s -> t.SetOrigSym(s)
t.OrigSym     -> t.OrigSym_()
}
'

cd types
rf '
mv Type.OrigSym Type.origSym
mv Type.OrigSym_ Type.OrigSym
'

: Revert types2 hack.
cd ../types2
git checkout HEAD^ .

Change-Id: I8eb17098613b1575df56b8189b1615823071d3d1
Reviewed-on: https://go-review.googlesource.com/c/go/+/345485
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Trust: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>