logmsg: Do not use NULL template_options parameter for log_macro_expand.

In case of time-related macros, it uses the members of the
LogTemplateOptions* structure, but it results in a NULL pointer
dereference. Instead of spraying the log_macro_expand code with NULL checks,
we pass an initialized options structure to the function, and wrap it
in the log_macro_expand_simple function.

Signed-off-by: Viktor Tusa <tusa@balabit.hu>
Signed-off-by: Balazs Scheidler <bazsi@balabit.hu>