go/types: make tracing configurable (matching types2)
This CL replaces the internal trace flag with Config.trace.
While unexported, it can still be set for testing via reflection.
The typical use is for manual tests, where -v (verbose) turns on
tracing output. Typical use:
go test -run Manual -v
This change makes go/types match types2 behavior.
Change-Id: I22842f4bba8fd632efe5929c950f4b1cab0a8569
Reviewed-on: https://go-review.googlesource.com/c/go/+/461081
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Griesemer <gri@google.com> Reviewed-by: Robert Griesemer <gri@google.com> Reviewed-by: Robert Findley <rfindley@google.com>