CVE-2024-7264: ASN.1 date parser overread

When a specially-crafted certificate is passed to `Curl_extract_certinfo` to parse, it may read bytes beyond the end of the buffer in which the certificate is held. According to the application, this may be a stack read overflow or a heap read overflow.

 524     /* Strip leading zeroes in fractional seconds. */
 525     for(fracl = tzp - fracp - 1; fracl && fracp[fracl - 1] == '0'; fracl--)
 526       ;