cmd/internal/objfile: emit better error for Go object of a different version

The Go object file format can change from version to version.
Tools like cmd/objdump and cmd/nm only onderstand the current
version of the object file. Currently, when it encounters an
object built with a different version of the toolchain, it emits
a generic error "unrecognized object file", which is not very
helpful for users. This CL makes it emit a clearer error. Now it
emits

objdump: open go116.o: go object of a different version: go116ld

Change-Id: I063c6078ed1da78f97cea65796779ae093a1a8cb
Reviewed-on: https://go-review.googlesource.com/c/go/+/315609


Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>