Incorrect number of shared memory blocks in disk thread

[jayanthc]

Test case: Set up shared memory using the vegas_setup_shmem_mode13 with X number of blocks in the disk thread. At this point, ipcs shows the correct (total) size for the shared memory. Run vegas_hpc_lbw. As the status monitor indicates during data acquisition (also verified by printing the n_block field of the vegas_databuf structure corresponding to the disk data buffer), the number of recognized blocks changes and the individual block size becomes 32MB. Probably related to Issue #10 .