Fix rand() not support on certain compiler

[AnnieRuru]

Pull Request Prelude

• I have followed proper Hercules code styling.
• I have read and understood the contribution guidelines before making this PR.
• I am aware that this PR will be closed if the above-mentioned criteria are not fulfilled.

Issues addressed

http://herc.ws/board/topic/16597-help-absorb-damage-taken-bonus/?do=findComment&comment=90812

Changes Proposed

change rand() into rnd()

Affected Branches

• Master

Known Issues and TODO List

none

[HerculesWSAPI]

This change is 

[4144]

Warnings what present in forum topic mean missing some includes

not sure is really need use standard rand function or custom rnd.
Hercules by itself using only custon rnd

[AnnieRuru]

use rnd() of course, search rnd() in our \src folder, all uses rnd(), not using rand()

only this sample plugin uses rand() which nobody bothers to load it