libvmon: use pread() instead of lseek()+read()

I had assumed pread wouldn't work on /proc files and that lseek to the
start was the only safe form of seeking, but this seems to be working
acceptably well even with buffer sizes of 2 requiring many sequential
reads per sample.

The lseek syscalls aren't free and it's nice to omit them entirely,
and we're essentially being sequential in our pread() use, and always
use a buffer that is large enough to fit everything in the first read
anyways.

0 files changed, 0 insertions, 0 deletions