bug#25360: File mode specification errors during building

[Eli Zaretskii]

> From: phillip.lord@russet.org.uk (Phillip Lord)
> Cc: rgm@gnu.org,  25360@debbugs.gnu.org
> Date: Fri, 13 Jan 2017 14:08:55 +0000
> 
> -  (search-backward "  GEN      loaddefs.el")
> +  (search-backward "-l loadup dump")
> +  (beginning-of-line)

Btw, relying on the likes of "  GEN      loaddefs.el" assumes the user
didn't say "make V=1", so I think it should be avoided anyway.