pidof: fix default behavior, add -x.

Before this patch, we're effectively doing `pidof -x` all the time. This
patch changes names_to_pid() to allow us to say whether or not we want to
include scripts, and adjusts the callers appropriately.

Also add tests for `pidof` versus `pidof -x` which pass after this
patch, without regressing the existing killall tests.
6 files changed