Subject: bug#11786: Use c_strcasecmp for portable ASCII case-insensitive comparison

From: Eli Zaretskii <[email-masked]>
Date: Tue, 26 Jun 2012 21:21:12 +0300

> Date: Tue, 26 Jun 2012 10:25:17 -0700
> From: Paul Eggert <[email-masked]>
> CC: Andreas Schwab <[email-masked]>, [email-masked], 
>  [email-masked]
> 
> c_strcasecmp does what you're saying (it uses c_tolower), and it's
> off-the-shelf code

So is xstrcasecmp.

> This shrinks and simplifies the source code of Emacs proper.

Your change neither shrinks nor simplifies anything.  It does the
exact opposite, in fact.