debug/elf: retain original error message when getSymbols fails.
The original error is currently discarded, and that makes it difficult
to know what failed, in case we want to retry only certain errors.
Change-Id: Id7e927ec242464249c4dfa5cda0f264adef3c898
Reviewed-on: https://go-review.googlesource.com/c/go/+/317851
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
Trust: Than McIntosh <thanm@google.com>