set icmp_code always to 0 even when -p option is used

[Felix Schladt]

Introduced with commit b34266b42b5f6f78b7346c9ca90caebcd59db345 the icmp_code field is no longer set to 0 due to the introduction of a memset of the whole struct to 0.
But with commit 6ff055115798166e172039284448be758b04e195 the "-p" option was introduced, which allows to fill empty bytes of the package with an arbitrary byte.
Since then the memset sets the whole struct to this byte and then fills in the individual fields, but the icmp_code field is never set to 0 as this line is commented out.

Kind regards,

Felix Schladt