bug#22991: 25.0.92: C-u C-s does not display "Regexp I-search:" in the echo area

[Kaushal Modi]

I also think that adding an option just for this is an overkill.

It makes sense that removing that cond right now would be a big behavior change and should not be done in emacs-25.

Can you guys please review and push the last patch I sent? Below are the 2 fixes:
1. Now C-u C-s shows the Regexp description if the search-default-mode is nil.
2. If regexp search is default, C-s does not show the Regexp description.

Let's continue this discussion in emacs-dev.

Thanks.

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Kaushal Modi