fix #3237 14 week powerdown

[economicstudio]

Fix #3237

• Floor -> Ceil
• Combine the zero new_vesting_withdraw_rate case.

Ceiling is fine (i.e., never withdraw more than requested in total) due to here:

steem/libraries/plugins/rc/rc_plugin.cpp

Line 89 in 7e50f3e

int64_t next_withdrawal = (withdraw_per_period <= total_left) ? withdraw_per_period : total_left;

Actually, the above is what prevents more withdrawal than requested in 14 week.

[TimCliff]

This would need to be wrapped in a hardfork check.

[economicstudio]

@TimCliff Thank you for your review. Unfortunately, STINC claims that it's intentional 👍 and closed the issue #3237.

While I agree that it's a tiny difference, I believe that money related problems (like #3184) should be avoided if possible. Is it good to show a user is still powering down for that tiny vest? If remaining withdrawal isn't calculated carefully, it's also prone to a bug to the front end (e.g., busyorg/busy#2159) since withdraw_rate is still the same (i.e., quite big for 14th week). Hope someone believes the same will fix this in the future. Many thanks!

ps. I'm absolutely fine if you or someone else close this.

[economicstudio]

In a case there might be a hardfork for SMT-lite or whatever, I've added hardfork check. @TimCliff Thanks.