[Core] Added fix for issue found by Coverity Scan.

The system resource will not be reclaimed and reused, reducing the
future availability of the resource.

In MMAP::​TerrainBuilder::​loadMap(unsigned int, unsigned int,
unsigned int, MMAP::​MeshData &, MMAP::​Spot):

Leak of memory or pointers to system resources (CWE-404)

Signed-off-by: Daniel S. Reichenbach <daniel@kogitoapp.com>