Overflow in interval loading in C module

[enapupe]

It seems there's a bug within psycopg-binary IntervalLoader implementation, this however can't be reproduced using the python version of IntervalLoader.

To reproduce the issue:

pip install psycopg

import psycopg

conn = psycopg.connect(user='postgres', password='postgres', dbname='postgres')

with conn.cursor() as cur:
    cur.execute("select ('1993534:40:40.447')::interval")
    row=cur.fetchone()
    print(row)

output from the above code: ✅
(datetime.timedelta(days=83063, seconds=81640, microseconds=447000),)

now pip install psycopg-binary and run the code again, it outputs: ❌
(datetime.timedelta(days=-16357, seconds=35048, microseconds=447000),)

It seems regular int is overflowing so long must be used for seconds, here's a rough patch

[dvarrazzo]

Hello! Thank you for the report! I'll leave you to work on #720, let me know if you need a hand on it.