Off-By-One Error in Subgraph Generation

[Jonathan-Rabideau]

On line 75 in subgraph_generator.cu, ceil() is useless with integer division.
Should be unsigned int chunkSize = (unsigned int)ceil((double)numActiveNodes / numThreads);

Results in not copying some data to the edge array, sending the old values to the kernel which results in undefined behavior; usually erroneous values in the last .01% of the nodes (but can propagate through the rest of the graph).