client: support per-client job files

client: support per-client job files

Currently the fio network client sends all job files to all clients.
This isn't very flexible.

Add support for specifying a specific job file for each client. Example:

$ fio --client hostname1 jobfile1 --client hostname2 jobfile2

would before add jobfile1 and jobfile2 as job files for both clients.
With this change, only jobfile1 is sent to hostname1, and only
jobfile2 is sent to hostname2.

Signed-off-by: Jens Axboe <axboe@kernel.dk>