[dev.link] cmd/link: remove unnecessary file processing from writelines
The linker DWARF-gen's line table writing routine contains a loop that
walks all abstract function DIEs looking for files that aren't
referenced in concrete function DIEs. Turns out this loop is no longer
necessary, most likely because the compiler emits an explicit DWARF
file table into the object file.
This patch removes the offending loop. This is a prelude to some
additional work that will hopefully get rid of file renumbering in
writelines altogether (still WIP).
Change-Id: I3b3a9acce1bae7dda878ab6de2d3436de302712e
Reviewed-on: https://go-review.googlesource.com/c/go/+/223145
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Jeremy Faller <jeremy@golang.org> Reviewed-by: Cherry Zhang <cherryyz@google.com>