cmd/go: use --ffile-prefix-map instead of --debug-prefix-map
Also add code to replace the vendor directory in the prefix-map in
vendored modules. We weren't doing that before because in vendored
modules, the module's Dir field was set to empty, so nothing was being
replaced. Instead when Dir is not set, so we are in vendor mode,
replace the entire vendor directory's path.
Change-Id: I910499c74237699fd36d18049909a72e2b6705d9
Reviewed-on: https://go-review.googlesource.com/c/go/+/478455 Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Michael Matloob <matloob@golang.org> Reviewed-by: Michael Matloob <matloob@golang.org>