CHANGE: skip argument check in ly_log()
CHANGE: skip argument check in ly_log()

NULL message string is allowed only for error messages (where the ly_errno
is set) and that situation is already checked by the log macro itself, so
don't test it in the logger function itself.

PavolVican/libyang,PavolVican/libyang,PavolVican/libyang,PavolVican/libyang,PavolVican/libyang,lukasmacko/libyang,lukasmacko/libyang