Add health counter to ust-app.c

Add health counter to ust-app.c

Any UST command can take an unknown amount of time to complete
especially with multiple applications and/or sessions even though it's
the correct behavior, the health check must not flag a bad health so
this patch adds a series of health code update to each ustctl actions in
ust-app.c.

Signed-off-by: David Goulet <dgoulet@efficios.com>