Make DEBUG macro definition variadic
    
    Update DEBUG macro definition to accept format string and its arguments
    as direct variadic macro arguments, instead of expecting them as an
    expression in parens.
    
    Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>
    Reviewed-by: Stephen Gallagher <sgallagh@redhat.com>
    Reviewed-by: Simo Sorce <simo@redhat.com>
    (cherry picked from commit cc026fd9ba386f2197e3217940d597dcad1a26fe)