cmd/compile: remove var sorting from DWARF inline generation

When generation DWARF inline info records, the current implementation
includes a sorting pass that reorders a subprogram's child variable
DIEs based on class (param/auto) and name. This sorting is no longer
needed, and can cause problems for a debugger (if we want to use the
DWARF info for creating a call to an optimized function); this patch
removes it.

Ordering of DWARF subprogram variable/parameter DIEs is still
deterministic with this change, since it is keyed off the order in
which vars appear in the pre-inlining function "Dcl" list.

Updates #27039

Change-Id: I3b91290d11bb3b9b36fb61271d80b801841401ee
Reviewed-on: https://go-review.googlesource.com/131895


Reviewed-by: Heschi Kreinick <heschi@google.com>