check-code: do not warn on printf \\x or \\[1-9]...
check-code: do not warn on printf \\x or \\[1-9]
When there is a double backslash the following char does not have any special
meaning. So do not warn on this.
Remove the now obsolete no-check-code statement. (It was used wrongly anyway, it
skipped checking the entire file.)
