Lock a vproc-local, read/write GLOP for reading or writing.
FNC_GLOP_Lock returns an integer that indicates success or failure.
|0||Lock was granted.|
|-1||The index is not valid or the map does not exist.|
|-2||The lock attempt timed out.|
|-3||Cannot lock a read-only GLOP.|
|-4||The GLOP is already locked by this routine. The routine may only perform one lock of any kind at a time.|