bug#24057: 25.1.50; ffap interprets comments beginning with "//" as file path

[Eli Zaretskii]

> From: Kaushal Modi <kaushal.modi@gmail.com>
> Date: Fri, 22 Jul 2016 23:00:00 +0000
> 
> (1) a major mode uses "//" as comment start chars, and
> (2) ido-mode is enabled, and
> (3) ffap feature is enabled, and
> (4) user does C-x C-f on a comment like "//foo"
> 
> attempt is made to access "//foo" path.

I see no reason to assume that file names cannot appear in comments.

> (3) Hit "C-x C-f"
> 
> You will see that emacs is trying to look for a path "//This"!
> 
> This must not happen.

I could agree with a user option to disable this behavior, but
disabling it unconditionally is IMO a mistake.

Thanks.