[dev.typeparams] cmd/compile: Fix handling of Name nodes during stenciling
The name substitution for stenciling was incorrectly handling non-local
names. Made changes to explicitly built the vars[] name substitution map
based on the local variables (similar to what inlining substitution
does). Then, we we are stenciling a name node, we do NOT make a copy of
the name node if it is not in vars[], since it is then a reference to an
external name. Added new function localvar() to create the new nodes for
the local variables and put them in the vars[] map.
New test listimp2.go, added missing test calls in list2.go
Change-Id: I8946478250c7bf2bd31c3247089bd50cfeeda0fd
Reviewed-on: https://go-review.googlesource.com/c/go/+/322190
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org>