ping uses a two-pass option parser. The first pass determines whether
ipv4 or ipv6 is desired, and the second parses the rest of the options.
But the first pass wrongly detects a '4' or '6' in an option's value as
a request to use ipv6 or ipv6 respectively, for example in an invocation
like "ping -c6 188.8.131.52".
Fix this confusion by including all options in the first round of
parsing, but ignoring those unrelated to ipv4/ipv6 selection.
Reported by: firstname.lastname@example.org
Submitted by: email@example.com
MFC after: 2 weeks