tests: check kill is converting signals names correctly

CC: Bernhard Voelker <mail@bernhard-voelker.de>
Signed-off-by: Sami Kerola <kerolasa@iki.fi>
tests: check various ways to specify kill signal

CC: Bernhard Voelker <mail@bernhard-voelker.de>
Signed-off-by: Sami Kerola <kerolasa@iki.fi>
tests: check kill print pid option

CC: Bernhard Voelker <mail@bernhard-voelker.de>
Signed-off-by: Sami Kerola <kerolasa@iki.fi>
tests: check kill all user processes

CC: Bernhard Voelker <mail@bernhard-voelker.de>
Signed-off-by: Sami Kerola <kerolasa@iki.fi>