Might as well provide a way around the mach-o munging
that doesn't require stripping all symbols.
After all, -w does mean no DWARF.

For #11887, #19734, and anyone else that needs to disable
this code path without losing the symbol table.

Change-Id: I254b7539f97fb9211fa90f446264b383e7f3980f
Reviewed-on: https://go-review.googlesource.com/39602
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>