Avoid crash if NULL is passed for filename/funcname in logging
Avoid crash if NULL is passed for filename/funcname in logging

The journald code would crash if a NULL was passed for the
filename / funcname in the logging code. This shouldn't
happen in general, but it is better to be safe, since there
have been bugs triggering this.

Signed-off-by: Daniel P. Berrange <bb938cf255e055ff3507f2627d214e8e62118fcf@redhat.com>

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