Sort DynidSyms to ensure a deterministic build.

Fix Solaris build.

Change-Id: I6c01cb3dec5e46b3d881e720e3c2079643b5c7c7
Reviewed-on: https://go-review.googlesource.com/c/go/+/230277


Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>