Fixed more instances of AA timers being eaten

Every time I touch zone/AA.cpp to fix timers it gets uglier.
This should fix the bug reported here: http://www.peqtgc.com/phpBB3/viewtopic.php?f=17&t=14125
It should also fix AAs not being reset when it when you have no buff slots free (confirmed on live)
Simplify conditional linking with libdl
Merge pull request #83 from AMDmi3/patch-1

Simplify conditional linking with libdl
Merge branch 'master' of git://github.com/EQEmu/Server