cvs "grep -io" displays matches in tolower() [bug-grep]

[Charles Levert]

Hi.

While studying the prline() function in src/grep.c, I
discovered that the "-io" (only_matching && match_icase)
code patch displays matches using the tolower() string it
locally constructs instead of the original one.

Also note that this approach of using tolower() on
individual C chars can't possibly be working with UTF-8
strings.

Is the tolower() stuff even needed there at all?
Other calls to (*execute)() don't seem to need it.
I think that check_multibyte_string() in search.c already
does all the necessary job.

There are two places in prline() where the tolower()
trick is performed.