bug#24914: 24.5; isearch-regexp: wrong error message

[Eli Zaretskii]

> From: Noam Postavsky <npostavs@users.sourceforge.net>
> Cc: drew.adams@oracle.com,  24914@debbugs.gnu.org
> Date: Sat, 09 Dec 2017 21:18:05 -0500
> 
> Unfortunately, all this discussion of int size seems to be academic.  I
> took another look at the code, there is another limit due to regexp
> opcode format.  We can raise the limit to 2^16-1 though.
> [...]
> Here is the updated patch:

LGTM for master.  Thanks for the research and for the patch.