Added fix for issue 1107254 on 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)