When porting the snapshot, a change was made to
dtop_get_file_line_amount() to initialize rc to -1. glibc defines
EoF as -1 thus causing the for loop to never get executed. A line count
of 0 was getting returnd thus causing ~1500 data points to not get
polled. Instead, initialize rc to 0.

Change-Id: I8e7a93f5efd535d662c13fa81cd5d0e421ad5a6b