test: execute other tests in a new session

The main reason is to execute tests without a control termnal and avoid
a case when tests try to use the --shell-job options.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/Makefile

@@ -17,9 +17,9 @@ all:
 TESTS = unix-callback mem-snap rpc libcriu mounts/ext security pipes crit socketpairs overlayfs
 
 other: .FORCE
-	for t in $(TESTS); do			\
-		$(MAKE) -C $$t run || exit 1;	\
-	done					\
+	for t in $(TESTS); do				\
+		setsid $(MAKE) -C $$t run || exit 1;	\
+	done						\
 
 zdtm-tst-list: zdtm.sh
 	./zdtm.sh -l > zdtm-tst-list