bug#22378: 24.5; hide-ifdef wrongly handles "#if defined X"

[Eli Zaretskii]

> Date: Fri, 15 Jan 2016 09:55:01 +0100 (CET)
> From: ydirson@free.fr
> 
> With the following text in buffer, with "hide some ifdefs" activated,
> when I define/undef A (and whether B is defined or not) the first block
> properly switches between "yes" and "no", whereas all ther others
> consistently stay at "yes"
> 
> ---->8----
> #ifdef A
> yes
> #else
> no
> #endif
> 
> #if defined A
> yes
> #else
> no
> #endif

I cannot reproduce this.  I tried both Emacs 24.5 and the current
emacs-25 branch, and both show the expected behavior.

Can you provide a step by step recipe, starting with "emacs -Q", to
reproduce the problem?