[GEN][ZH] Fix memory leak in SpecialAbilityUpdate::isWithinStartAbilityRange()

[xezon]

• Relates to The disabled binary shower particle effect causes a memory leak and eventual crash #181

This change fixes a minor memory leak in SpecialAbilityUpdate::isWithinStartAbilityRange(). It is reproducible when using the China Hacker to disable buildings.

Leaked a block of size 16, tagstring D:\Projects\TheSuperHackers\GeneralsGameCode\GeneralsMD\Code\GameEngine\Source\GameLogic\Object\SimpleObjectIterator.cpp, from pool/dma SimpleObjectIteratorClumpPool
Leaked a block of size 16, tagstring D:\Projects\TheSuperHackers\GeneralsGameCode\GeneralsMD\Code\GameEngine\Source\GameLogic\Object\SimpleObjectIterator.cpp, from pool/dma SimpleObjectIteratorClumpPool
Leaked a block of size 16, tagstring D:\Projects\TheSuperHackers\GeneralsGameCode\GeneralsMD\Code\GameEngine\Source\GameLogic\Object\SimpleObjectIterator.cpp, from pool/dma SimpleObjectIteratorClumpPool
...
Leaked a block of size 16, tagstring D:\Projects\TheSuperHackers\GeneralsGameCode\GeneralsMD\Code\GameEngine\Source\GameLogic\Object\PartitionManager.cpp, from pool/dma SimpleObjectIteratorPool
Leaked a block of size 16, tagstring D:\Projects\TheSuperHackers\GeneralsGameCode\GeneralsMD\Code\GameEngine\Source\GameLogic\Object\PartitionManager.cpp, from pool/dma SimpleObjectIteratorPool
Leaked a block of size 16, tagstring D:\Projects\TheSuperHackers\GeneralsGameCode\GeneralsMD\Code\GameEngine\Source\GameLogic\Object\PartitionManager.cpp, from pool/dma SimpleObjectIteratorPool
...
ASSERTION FAILURE: There were 5089 memory leaks. Please fix them.

[Mauller]

Looks good, checked this out and could see these being leaked every time the hackers started a new hacking session when disabling the building.