test/other: add a test to check the --shell-job option

This test creates a pty pair, creates a test process and sets a slave
pty as control terminal for it.

Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

scripts/travis/travis-tests

@@ -127,6 +127,8 @@ ip net add test
 
 ./test/zdtm.py run --empty-ns -T zdtm/static/socket-tcp*-local --iter 2
 
+make -C test/others/shell-job
+
 pip install flake8
 make lint