proxy_hcheck: Expr name in balancer manager after graceful restart

[Rainer Jung]

The name shown in the Expr table of the balancer manager changes after a 
graceful restart. Before restart it is the symbolic name used in the 
config, e.g. ok234. After the restart it is the full path name of the 
shared memory file.

The expression itself shown in the second column is OK before and after, 
also the expr name given in the worker table.

Regards,

Rainer