string::compare() will be faster when string::find's result is
compared with 0, because it will not scan the whole string.

Change-Id: I78596a6d796fe9779f88b7c7b91da09aa27b7035
Reviewed-on: https://gerrit.libreoffice.org/32430Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Julien Nabet <serval2412@yahoo.fr>