fix: do not overwrite files while Cflag_count reaches Wflag

[ManzeonYip]

When the number of files reaches the specified value, avoid cyclic packet capturing from overwriting the already captured files.

[fxlb]

The man page states:

       -W filecount
              Used in conjunction with the -C option, this will limit the num-
              ber  of  files  created to the specified number, and begin over-
              writing files from the beginning,  thus  creating  a  'rotating'
              buffer.  In addition, it will name the files with enough leading
              0s to support the maximum number of files, allowing them to sort
              correctly.

Have you noticed any anomalies about the usage?

[guyharris]

I.e., this is the intended behavior of the flag -W n - to keep around only the past n files.

Are you seeing this behavior when the -C flag is specified but the -W flag is not specified?

[fxlb]

@ManzeonYip Any answers to Guy's questions?