ktop should verify size of commits

ktop gets from the kernel how many bytes of data are in the records
it just read. It needs to check this number.

Sometime, the commit field has 0xffffffffc0000000 added to it.
Not sure what it means, but just taking the lower bits seems to
work well. I've filed a defect to further expore what this big
number means.

BUG=chromium-os:38502
TEST=ran ktop, checked for bad values

Change-Id: I4243e99aca6722fb6aa6695191ecbca9d3eef562
Reviewed-on: https://gerrit.chromium.org/gerrit/42474
Reviewed-by: Luigi Semenzato <semenzato@chromium.org>
Commit-Queue: Paul Taysom <taysom@chromium.org>
Tested-by: Paul Taysom <taysom@chromium.org>
2 files changed