gitweb: Call to_utf8() on input string in chop_and_escape_str()

gitweb: Call to_utf8() on input string in chop_and_escape_str()

a) To fix the comparison with the chopped string,
   otherwise we compare bytes with characters, as
   chop_str() must run to_utf8() for correct operation
b) To give the title attribute correct encoding;
   we need to mark strings as UTF-8 before outpur

Signed-off-by: Jürgen Kreileder <jk@blackdown.de>
Acked-by: Jakub Narębski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>