[z2164] Use Pool system for BG buff

Drop not required manual handling of BG-Objects

Signed-off-by: Schmoozerd <schmoozerd@cmangos>

(based on commit [12242] - cd9563c)

(based on commit [s1796] - b7dbf5a)
[z2165] Fix Extracting for cmake.

(based on commit [12243] - a4b3bc5)

(based on commit [s1797] - ce57530)