clatd: rework sigterm & error handling

Separate 'running' flag out into 'running' and 'sigterm',
and make SIGTERM handler the only thing that sets 'sigterm'.

running is cleared via catastrophic errors, ie. EOF and ENETDOWN

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I8254c3f4643d60feff1cb32aaa9784dca18e138c
3 files changed