Avoid two unsigned int overflows in FTP listing parser #3225
Curl_ftp_parselist: avoid unsigned integer overflows detected by clang
The overflow has no real world impact.
With any input and first char no being a digit (0-9), the execution
Then the execution goes straight to L1007 which causes the second
A simple 'continue' in L408 instead of 'i--' avoids both warnings.