nss: Promote debug message to proper error when time() fails

nss: Promote debug message to proper error when time() fails

The difference between DEBUG() and ERROR() macros is that the
latter also prints (stringified) errno. Inside of findLease()
there's one line where time() is called which is documented as:

  On error, ((time_t) -1) is returned, and errno is set to
  indicate the error.

Therefore, don't just print DEBUG() but ERROR() so that the cause
for the error is printed too.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>