fuzz: skip the text round trip of the smallest interval time

[tamnd]

Part of #3.

The M2 fuzz run on server2 found one crash in type_recv. The input is an interval in the binary format whose time is the smallest int64. The receive function accepts it and the output is -21 years -4 mons -61697 days -2562047788:00:54.775808. The input function then refuses that text with 22007, and the target panics on the text round trip.

PostgreSQL does the same thing. On the oracle, '-2562047788:00:54.775808'::interval gives invalid input syntax for type interval with 22007, and '-2562047788:00:54.775807'::interval is correct. Thus rupg is correct and the check in the target is too strict for this one value.

What changes

• type_recv does not do the text round trip when an interval or an interval[] holds the time -2562047788:00:54.775808. The binary round trip still runs for that value.

Test

• I replayed the crash input on server1 with a small example that builds the RecvCase the same way as libFuzzer. Without the change it panics at the text round trip. With the change it passes.
• cargo clippy --lib -- -D warnings in fuzz is clean.
• srvtest passed on server1.